summaryrefslogtreecommitdiffstats
path: root/kernel
Commit message (Collapse)AuthorAgeFilesLines
* bpf, lockdown, audit: Fix buggy SELinux lockdown permission checksDaniel Borkmann2021-06-022-22/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 59438b46471a ("security,lockdown,selinux: implement SELinux lockdown") added an implementation of the locked_down LSM hook to SELinux, with the aim to restrict which domains are allowed to perform operations that would breach lockdown. This is indirectly also getting audit subsystem involved to report events. The latter is problematic, as reported by Ondrej and Serhei, since it can bring down the whole system via audit: 1) The audit events that are triggered due to calls to security_locked_down() can OOM kill a machine, see below details [0]. 2) It also seems to be causing a deadlock via avc_has_perm()/slow_avc_audit() when trying to wake up kauditd, for example, when using trace_sched_switch() tracepoint, see details in [1]. Triggering this was not via some hypothetical corner case, but with existing tools like runqlat & runqslower from bcc, for example, which make use of this tracepoint. Rough call sequence goes like: rq_lock(rq) -> -------------------------+ trace_sched_switch() -> | bpf_prog_xyz() -> +-> deadlock selinux_lockdown() -> | audit_log_end() -> | wake_up_interruptible() -> | try_to_wake_up() -> | rq_lock(rq) --------------+ What's worse is that the intention of 59438b46471a to further restrict lockdown settings for specific applications in respect to the global lockdown policy is completely broken for BPF. The SELinux policy rule for the current lockdown check looks something like this: allow <who> <who> : lockdown { <reason> }; However, this doesn't match with the 'current' task where the security_locked_down() is executed, example: httpd does a syscall. There is a tracing program attached to the syscall which triggers a BPF program to run, which ends up doing a bpf_probe_read_kernel{,_str}() helper call. The selinux_lockdown() hook does the permission check against 'current', that is, httpd in this example. httpd has literally zero relation to this tracing program, and it would be nonsensical having to write an SELinux policy rule against httpd to let the tracing helper pass. The policy in this case needs to be against the entity that is installing the BPF program. For example, if bpftrace would generate a histogram of syscall counts by user space application: bpftrace -e 'tracepoint:raw_syscalls:sys_enter { @[comm] = count(); }' bpftrace would then go and generate a BPF program from this internally. One way of doing it [for the sake of the example] could be to call bpf_get_current_task() helper and then access current->comm via one of bpf_probe_read_kernel{,_str}() helpers. So the program itself has nothing to do with httpd or any other random app doing a syscall here. The BPF program _explicitly initiated_ the lockdown check. The allow/deny policy belongs in the context of bpftrace: meaning, you want to grant bpftrace access to use these helpers, but other tracers on the system like my_random_tracer _not_. Therefore fix all three issues at the same time by taking a completely different approach for the security_locked_down() hook, that is, move the check into the program verification phase where we actually retrieve the BPF func proto. This also reliably gets the task (current) that is trying to install the BPF tracing program, e.g. bpftrace/bcc/perf/systemtap/etc, and it also fixes the OOM since we're moving this out of the BPF helper's fast-path which can be called several millions of times per second. The check is then also in line with other security_locked_down() hooks in the system where the enforcement is performed at open/load time, for example, open_kcore() for /proc/kcore access or module_sig_check() for module signatures just to pick few random ones. What's out of scope in the fix as well as in other security_locked_down() hook locations /outside/ of BPF subsystem is that if the lockdown policy changes on the fly there is no retrospective action. This requires a different discussion, potentially complex infrastructure, and it's also not clear whether this can be solved generically. Either way, it is out of scope for a suitable stable fix which this one is targeting. Note that the breakage is specifically on 59438b46471a where it started to rely on 'current' as UAPI behavior, and _not_ earlier infrastructure such as 9d1f8be5cf42 ("bpf: Restrict bpf when kernel lockdown is in confidentiality mode"). [0] https://bugzilla.redhat.com/show_bug.cgi?id=1955585, Jakub Hrozek says: I starting seeing this with F-34. When I run a container that is traced with BPF to record the syscalls it is doing, auditd is flooded with messages like: type=AVC msg=audit(1619784520.593:282387): avc: denied { confidentiality } for pid=476 comm="auditd" lockdown_reason="use of bpf to read kernel RAM" scontext=system_u:system_r:auditd_t:s0 tcontext=system_u:system_r:auditd_t:s0 tclass=lockdown permissive=0 This seems to be leading to auditd running out of space in the backlog buffer and eventually OOMs the machine. [...] auditd running at 99% CPU presumably processing all the messages, eventually I get: Apr 30 12:20:42 fedora kernel: audit: backlog limit exceeded Apr 30 12:20:42 fedora kernel: audit: backlog limit exceeded Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152579 > audit_backlog_limit=64 Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152626 > audit_backlog_limit=64 Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152694 > audit_backlog_limit=64 Apr 30 12:20:42 fedora kernel: audit: audit_lost=6878426 audit_rate_limit=0 audit_backlog_limit=64 Apr 30 12:20:45 fedora kernel: oci-seccomp-bpf invoked oom-killer: gfp_mask=0x100cca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=-1000 Apr 30 12:20:45 fedora kernel: CPU: 0 PID: 13284 Comm: oci-seccomp-bpf Not tainted 5.11.12-300.fc34.x86_64 #1 Apr 30 12:20:45 fedora kernel: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014 [...] [1] https://lore.kernel.org/linux-audit/CANYvDQN7H5tVp47fbYcRasv4XF07eUbsDwT_eDCHXJUj43J7jQ@mail.gmail.com/, Serhei Makarov says: Upstream kernel 5.11.0-rc7 and later was found to deadlock during a bpf_probe_read_compat() call within a sched_switch tracepoint. The problem is reproducible with the reg_alloc3 testcase from SystemTap's BPF backend testsuite on x86_64 as well as the runqlat, runqslower tools from bcc on ppc64le. Example stack trace: [...] [ 730.868702] stack backtrace: [ 730.869590] CPU: 1 PID: 701 Comm: in:imjournal Not tainted, 5.12.0-0.rc2.20210309git144c79ef3353.166.fc35.x86_64 #1 [ 730.871605] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014 [ 730.873278] Call Trace: [ 730.873770] dump_stack+0x7f/0xa1 [ 730.874433] check_noncircular+0xdf/0x100 [ 730.875232] __lock_acquire+0x1202/0x1e10 [ 730.876031] ? __lock_acquire+0xfc0/0x1e10 [ 730.876844] lock_acquire+0xc2/0x3a0 [ 730.877551] ? __wake_up_common_lock+0x52/0x90 [ 730.878434] ? lock_acquire+0xc2/0x3a0 [ 730.879186] ? lock_is_held_type+0xa7/0x120 [ 730.880044] ? skb_queue_tail+0x1b/0x50 [ 730.880800] _raw_spin_lock_irqsave+0x4d/0x90 [ 730.881656] ? __wake_up_common_lock+0x52/0x90 [ 730.882532] __wake_up_common_lock+0x52/0x90 [ 730.883375] audit_log_end+0x5b/0x100 [ 730.884104] slow_avc_audit+0x69/0x90 [ 730.884836] avc_has_perm+0x8b/0xb0 [ 730.885532] selinux_lockdown+0xa5/0xd0 [ 730.886297] security_locked_down+0x20/0x40 [ 730.887133] bpf_probe_read_compat+0x66/0xd0 [ 730.887983] bpf_prog_250599c5469ac7b5+0x10f/0x820 [ 730.888917] trace_call_bpf+0xe9/0x240 [ 730.889672] perf_trace_run_bpf_submit+0x4d/0xc0 [ 730.890579] perf_trace_sched_switch+0x142/0x180 [ 730.891485] ? __schedule+0x6d8/0xb20 [ 730.892209] __schedule+0x6d8/0xb20 [ 730.892899] schedule+0x5b/0xc0 [ 730.893522] exit_to_user_mode_prepare+0x11d/0x240 [ 730.894457] syscall_exit_to_user_mode+0x27/0x70 [ 730.895361] entry_SYSCALL_64_after_hwframe+0x44/0xae [...] Fixes: 59438b46471a ("security,lockdown,selinux: implement SELinux lockdown") Reported-by: Ondrej Mosnacek <omosnace@redhat.com> Reported-by: Jakub Hrozek <jhrozek@redhat.com> Reported-by: Serhei Makarov <smakarov@redhat.com> Reported-by: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Tested-by: Jiri Olsa <jolsa@redhat.com> Cc: Paul Moore <paul@paul-moore.com> Cc: James Morris <jamorris@linux.microsoft.com> Cc: Jerome Marchand <jmarchan@redhat.com> Cc: Frank Eigler <fche@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Link: https://lore.kernel.org/bpf/01135120-8bf7-df2e-cff0-1d73f1f841c3@iogearbox.net
* Merge tag 'net-5.13-rc4' of ↵Linus Torvalds2021-05-268-72/+216
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net Pull networking fixes from Jakub Kicinski: "Networking fixes for 5.13-rc4, including fixes from bpf, netfilter, can and wireless trees. Notably including fixes for the recently announced "FragAttacks" WiFi vulnerabilities. Rather large batch, touching some core parts of the stack, too, but nothing hair-raising. Current release - regressions: - tipc: make node link identity publish thread safe - dsa: felix: re-enable TAS guard band mode - stmmac: correct clocks enabled in stmmac_vlan_rx_kill_vid() - stmmac: fix system hang if change mac address after interface ifdown Current release - new code bugs: - mptcp: avoid OOB access in setsockopt() - bpf: Fix nested bpf_bprintf_prepare with more per-cpu buffers - ethtool: stats: fix a copy-paste error - init correct array size Previous releases - regressions: - sched: fix packet stuck problem for lockless qdisc - net: really orphan skbs tied to closing sk - mlx4: fix EEPROM dump support - bpf: fix alu32 const subreg bound tracking on bitwise operations - bpf: fix mask direction swap upon off reg sign change - bpf, offload: reorder offload callback 'prepare' in verifier - stmmac: Fix MAC WoL not working if PHY does not support WoL - packetmmap: fix only tx timestamp on request - tipc: skb_linearize the head skb when reassembling msgs Previous releases - always broken: - mac80211: address recent "FragAttacks" vulnerabilities - mac80211: do not accept/forward invalid EAPOL frames - mptcp: avoid potential error message floods - bpf, ringbuf: deny reserve of buffers larger than ringbuf to prevent out of buffer writes - bpf: forbid trampoline attach for functions with variable arguments - bpf: add deny list of functions to prevent inf recursion of tracing programs - tls splice: check SPLICE_F_NONBLOCK instead of MSG_DONTWAIT - can: isotp: prevent race between isotp_bind() and isotp_setsockopt() - netfilter: nft_set_pipapo_avx2: Add irq_fpu_usable() check, fallback to non-AVX2 version Misc: - bpf: add kconfig knob for disabling unpriv bpf by default" * tag 'net-5.13-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (172 commits) net: phy: Document phydev::dev_flags bits allocation mptcp: validate 'id' when stopping the ADD_ADDR retransmit timer mptcp: avoid error message on infinite mapping mptcp: drop unconditional pr_warn on bad opt mptcp: avoid OOB access in setsockopt() nfp: update maintainer and mailing list addresses net: mvpp2: add buffer header handling in RX bnx2x: Fix missing error code in bnx2x_iov_init_one() net: zero-initialize tc skb extension on allocation net: hns: Fix kernel-doc sctp: fix the proc_handler for sysctl encap_port sctp: add the missing setting for asoc encap_port bpf, selftests: Adjust few selftest result_unpriv outcomes bpf: No need to simulate speculative domain for immediates bpf: Fix mask direction swap upon off reg sign change bpf: Wrap aux data inside bpf_sanitize_info container bpf: Fix BPF_LSM kconfig symbol dependency selftests/bpf: Add test for l3 use of bpf_redirect_peer bpftool: Add sock_release help info for cgroup attach/prog load command net: dsa: microchip: enable phy errata workaround on 9567 ...
| * bpf: No need to simulate speculative domain for immediatesDaniel Borkmann2021-05-251-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In 801c6058d14a ("bpf: Fix leakage of uninitialized bpf stack under speculation") we replaced masking logic with direct loads of immediates if the register is a known constant. Given in this case we do not apply any masking, there is also no reason for the operation to be truncated under the speculative domain. Therefore, there is also zero reason for the verifier to branch-off and simulate this case, it only needs to do it for unknown but bounded scalars. As a side-effect, this also enables few test cases that were previously rejected due to simulation under zero truncation. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org>
| * bpf: Fix mask direction swap upon off reg sign changeDaniel Borkmann2021-05-251-10/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Masking direction as indicated via mask_to_left is considered to be calculated once and then used to derive pointer limits. Thus, this needs to be placed into bpf_sanitize_info instead so we can pass it to sanitize_ptr_alu() call after the pointer move. Piotr noticed a corner case where the off reg causes masking direction change which then results in an incorrect final aux->alu_limit. Fixes: 7fedb63a8307 ("bpf: Tighten speculative pointer arithmetic mask") Reported-by: Piotr Krysiuk <piotras@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org>
| * bpf: Wrap aux data inside bpf_sanitize_info containerDaniel Borkmann2021-05-251-7/+11
| | | | | | | | | | | | | | | | | | | | | | Add a container structure struct bpf_sanitize_info which holds the current aux info, and update call-sites to sanitize_ptr_alu() to pass it in. This is needed for passing in additional state later on. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: Piotr Krysiuk <piotras@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org>
| * bpf: Fix BPF_LSM kconfig symbol dependencyDaniel Borkmann2021-05-251-0/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Similarly as 6bdacdb48e94 ("bpf: Fix BPF_JIT kconfig symbol dependency") we need to detangle the hard BPF_LSM dependency on NET. This was previously implicit by its dependency on BPF_JIT which itself was dependent on NET (but without any actual/real hard dependency code-wise). Given the latter was lifted, so should be the former as BPF_LSMs could well exist on net-less systems. This therefore also fixes a randconfig build error recently reported by Randy: ld: kernel/bpf/bpf_lsm.o: in function `bpf_lsm_func_proto': bpf_lsm.c:(.text+0x1a0): undefined reference to `bpf_sk_storage_get_proto' ld: bpf_lsm.c:(.text+0x1b8): undefined reference to `bpf_sk_storage_delete_proto' [...] Fixes: b24abcff918a ("bpf, kconfig: Add consolidated menu entry for bpf with core options") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Randy Dunlap <rdunlap@infradead.org> Tested-by: Randy Dunlap <rdunlap@infradead.org>
| * bpf, offload: Reorder offload callback 'prepare' in verifierYinjun Zhang2021-05-201-6/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 4976b718c355 ("bpf: Introduce pseudo_btf_id") switched the order of resolve_pseudo_ldimm(), in which some pseudo instructions are rewritten. Thus those rewritten instructions cannot be passed to driver via 'prepare' offload callback. Reorder the 'prepare' offload callback to fix it. Fixes: 4976b718c355 ("bpf: Introduce pseudo_btf_id") Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com> Signed-off-by: Simon Horman <simon.horman@netronome.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20210520085834.15023-1-simon.horman@netronome.com
| * bpf: Avoid using ARRAY_SIZE on an uninitialized pointerFlorent Revest2021-05-201-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The cppcheck static code analysis reported the following error: if (WARN_ON_ONCE(nest_level > ARRAY_SIZE(bufs->tmp_bufs))) { ^ ARRAY_SIZE is a macro that expands to sizeofs, so bufs is not actually dereferenced at runtime, and the code is actually safe. But to keep things tidy, this patch removes the need for a call to ARRAY_SIZE by extracting the size of the array into a macro. Cppcheck should no longer be confused and the code ends up being a bit cleaner. Fixes: e2d5b2bb769f ("bpf: Fix nested bpf_bprintf_prepare with more per-cpu buffers") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Florent Revest <revest@chromium.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/bpf/20210517092830.1026418-2-revest@chromium.org
| * bpf: Clarify a bpf_bprintf_prepare macroFlorent Revest2021-05-201-4/+5
| | | | | | | | | | | | | | | | | | | | | | The per-cpu buffers contain bprintf data rather than printf arguments. The macro name and comment were a bit confusing, this rewords them in a clearer way. Signed-off-by: Florent Revest <revest@chromium.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Song Liu <song@kernel.org> Link: https://lore.kernel.org/bpf/20210517092830.1026418-1-revest@chromium.org
| * bpf: Fix BPF_JIT kconfig symbol dependencyDaniel Borkmann2021-05-201-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Randy reported a randconfig build error recently on i386: ld: arch/x86/net/bpf_jit_comp32.o: in function `do_jit': bpf_jit_comp32.c:(.text+0x28c9): undefined reference to `__bpf_call_base' ld: arch/x86/net/bpf_jit_comp32.o: in function `bpf_int_jit_compile': bpf_jit_comp32.c:(.text+0x3694): undefined reference to `bpf_jit_blind_constants' ld: bpf_jit_comp32.c:(.text+0x3719): undefined reference to `bpf_jit_binary_free' ld: bpf_jit_comp32.c:(.text+0x3745): undefined reference to `bpf_jit_binary_alloc' ld: bpf_jit_comp32.c:(.text+0x37d3): undefined reference to `bpf_jit_prog_release_other' [...] The cause was that b24abcff918a ("bpf, kconfig: Add consolidated menu entry for bpf with core options") moved BPF_JIT from net/Kconfig into kernel/bpf/Kconfig and previously BPF_JIT was guarded by a 'if NET'. However, there is no actual dependency on NET, it's just that menuconfig NET selects BPF. And the latter in turn causes kernel/bpf/core.o to be built which contains above symbols. Randy's randconfig didn't have NET set, and BPF wasn't either, but BPF_JIT otoh was. Detangle this by making BPF_JIT depend on BPF instead. arm64 was the only arch that pulled in its JIT in net/ via obj-$(CONFIG_NET), all others unconditionally pull this dir in via obj-y. Do the same since CONFIG_NET guard there is really useless as we compiled the JIT via obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o anyway. Fixes: b24abcff918a ("bpf, kconfig: Add consolidated menu entry for bpf with core options") Reported-by: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Randy Dunlap <rdunlap@infradead.org> Tested-by: Randy Dunlap <rdunlap@infradead.org>
| * Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpfDavid S. Miller2021-05-117-45/+174
| |\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Daniel Borkmann says: ==================== pull-request: bpf 2021-05-11 The following pull-request contains BPF updates for your *net* tree. We've added 13 non-merge commits during the last 8 day(s) which contain a total of 21 files changed, 817 insertions(+), 382 deletions(-). The main changes are: 1) Fix multiple ringbuf bugs in particular to prevent writable mmap of read-only pages, from Andrii Nakryiko & Thadeu Lima de Souza Cascardo. 2) Fix verifier alu32 known-const subregister bound tracking for bitwise operations and/or/xor, from Daniel Borkmann. 3) Reject trampoline attachment for functions with variable arguments, and also add a deny list of other forbidden functions, from Jiri Olsa. 4) Fix nested bpf_bprintf_prepare() calls used by various helpers by switching to per-CPU buffers, from Florent Revest. 5) Fix kernel compilation with BTF debug info on ppc64 due to pahole missing TCP-CC functions like cubictcp_init, from Martin KaFai Lau. 6) Add a kconfig entry to provide an option to disallow unprivileged BPF by default, from Daniel Borkmann. 7) Fix libbpf compilation for older libelf when GELF_ST_VISIBILITY() macro is not available, from Arnaldo Carvalho de Melo. 8) Migrate test_tc_redirect to test_progs framework as prep work for upcoming skb_change_head() fix & selftest, from Jussi Maki. 9) Fix a libbpf segfault in add_dummy_ksym_var() if BTF is not present, from Ian Rogers. 10) Fix tx_only micro-benchmark in xdpsock BPF sample with proper frame size, from Magnus Karlsson. ==================== Signed-off-by: David S. Miller <davem@davemloft.net>
| | * bpf: Fix nested bpf_bprintf_prepare with more per-cpu buffersFlorent Revest2021-05-111-13/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The bpf_seq_printf, bpf_trace_printk and bpf_snprintf helpers share one per-cpu buffer that they use to store temporary data (arguments to bprintf). They "get" that buffer with try_get_fmt_tmp_buf and "put" it by the end of their scope with bpf_bprintf_cleanup. If one of these helpers gets called within the scope of one of these helpers, for example: a first bpf program gets called, uses bpf_trace_printk which calls raw_spin_lock_irqsave which is traced by another bpf program that calls bpf_snprintf, then the second "get" fails. Essentially, these helpers are not re-entrant. They would return -EBUSY and print a warning message once. This patch triples the number of bprintf buffers to allow three levels of nesting. This is very similar to what was done for tracepoints in "9594dc3c7e7 bpf: fix nested bpf tracepoints with per-cpu data" Fixes: d9c9e4db186a ("bpf: Factorize bpf_trace_printk and bpf_seq_printf") Reported-by: syzbot+63122d0bc347f18c1884@syzkaller.appspotmail.com Signed-off-by: Florent Revest <revest@chromium.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210511081054.2125874-1-revest@chromium.org
| | * bpf: Add deny list of btf ids check for tracing programsJiri Olsa2021-05-111-0/+14
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The recursion check in __bpf_prog_enter and __bpf_prog_exit leaves some (not inlined) functions unprotected: In __bpf_prog_enter: - migrate_disable is called before prog->active is checked In __bpf_prog_exit: - migrate_enable,rcu_read_unlock_strict are called after prog->active is decreased When attaching trampoline to them we get panic like: traps: PANIC: double fault, error_code: 0x0 double fault: 0000 [#1] SMP PTI RIP: 0010:__bpf_prog_enter+0x4/0x50 ... Call Trace: <IRQ> bpf_trampoline_6442466513_0+0x18/0x1000 migrate_disable+0x5/0x50 __bpf_prog_enter+0x9/0x50 bpf_trampoline_6442466513_0+0x18/0x1000 migrate_disable+0x5/0x50 __bpf_prog_enter+0x9/0x50 bpf_trampoline_6442466513_0+0x18/0x1000 migrate_disable+0x5/0x50 __bpf_prog_enter+0x9/0x50 bpf_trampoline_6442466513_0+0x18/0x1000 migrate_disable+0x5/0x50 ... Fixing this by adding deny list of btf ids for tracing programs and checking btf id during program verification. Adding above functions to this list. Suggested-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20210429114712.43783-1-jolsa@kernel.org
| | * bpf: Add kconfig knob for disabling unpriv bpf by defaultDaniel Borkmann2021-05-113-6/+36
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Add a kconfig knob which allows for unprivileged bpf to be disabled by default. If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2. This still allows a transition of 2 -> {0,1} through an admin. Similarly, this also still keeps 1 -> {1} behavior intact, so that once set to permanently disabled, it cannot be undone aside from a reboot. We've also added extra2 with max of 2 for the procfs handler, so that an admin still has a chance to toggle between 0 <-> 2. Either way, as an additional alternative, applications can make use of CAP_BPF that we added a while ago. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
| | * bpf, kconfig: Add consolidated menu entry for bpf with core optionsDaniel Borkmann2021-05-111-0/+78
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Right now, all core BPF related options are scattered in different Kconfig locations mainly due to historic reasons. Moving forward, lets add a proper subsystem entry under ... General setup ---> BPF subsystem ---> ... in order to have all knobs in a single location and thus ease BPF related configuration. Networking related bits such as sockmap are out of scope for the general setup and therefore better suited to remain in net/Kconfig. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/f23f58765a4d59244ebd8037da7b6a6b2fb58446.1620765074.git.daniel@iogearbox.net
| | * bpf: Prevent writable memory-mapping of read-only ringbuf pagesAndrii Nakryiko2021-05-111-13/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Only the very first page of BPF ringbuf that contains consumer position counter is supposed to be mapped as writeable by user-space. Producer position is read-only and can be modified only by the kernel code. BPF ringbuf data pages are read-only as well and are not meant to be modified by user-code to maintain integrity of per-record headers. This patch allows to map only consumer position page as writeable and everything else is restricted to be read-only. remap_vmalloc_range() internally adds VM_DONTEXPAND, so all the established memory mappings can't be extended, which prevents any future violations through mremap()'ing. Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") Reported-by: Ryota Shiga (Flatt Security) Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org>
| | * bpf, ringbuf: Deny reserve of buffers larger than ringbufThadeu Lima de Souza Cascardo2021-05-111-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A BPF program might try to reserve a buffer larger than the ringbuf size. If the consumer pointer is way ahead of the producer, that would be successfully reserved, allowing the BPF program to read or write out of the ringbuf allocated area. Reported-by: Ryota Shiga (Flatt Security) Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Acked-by: Alexei Starovoitov <ast@kernel.org>
| | * bpf: Fix alu32 const subreg bound tracking on bitwise operationsDaniel Borkmann2021-05-111-13/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix a bug in the verifier's scalar32_min_max_*() functions which leads to incorrect tracking of 32 bit bounds for the simulation of and/or/xor bitops. When both the src & dst subreg is a known constant, then the assumption is that scalar_min_max_*() will take care to update bounds correctly. However, this is not the case, for example, consider a register R2 which has a tnum of 0xffffffff00000000, meaning, lower 32 bits are known constant and in this case of value 0x00000001. R2 is then and'ed with a register R3 which is a 64 bit known constant, here, 0x100000002. What can be seen in line '10:' is that 32 bit bounds reach an invalid state where {u,s}32_min_value > {u,s}32_max_value. The reason is scalar32_min_max_*() delegates 32 bit bounds updates to scalar_min_max_*(), however, that really only takes place when both the 64 bit src & dst register is a known constant. Given scalar32_min_max_*() is intended to be designed as closely as possible to scalar_min_max_*(), update the 32 bit bounds in this situation through __mark_reg32_known() which will set all {u,s}32_{min,max}_value to the correct constant, which is 0x00000000 after the fix (given 0x00000001 & 0x00000002 in 32 bit space). This is possible given var32_off already holds the final value as dst_reg->var_off is updated before calling scalar32_min_max_*(). Before fix, invalid tracking of R2: [...] 9: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=-9223372036854775807 (0x8000000000000001),smax_value=9223372032559808513 (0x7fffffff00000001),umin_value=1,umax_value=0xffffffff00000001,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_min_value=1,u32_max_value=1) R3_w=inv4294967298 R10=fp0 9: (5f) r2 &= r3 10: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=0,smax_value=4294967296 (0x100000000),umin_value=0,umax_value=0x100000000,var_off=(0x0; 0x100000000),s32_min_value=1,s32_max_value=0,u32_min_value=1,u32_max_value=0) R3_w=inv4294967298 R10=fp0 [...] After fix, correct tracking of R2: [...] 9: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=-9223372036854775807 (0x8000000000000001),smax_value=9223372032559808513 (0x7fffffff00000001),umin_value=1,umax_value=0xffffffff00000001,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_min_value=1,u32_max_value=1) R3_w=inv4294967298 R10=fp0 9: (5f) r2 &= r3 10: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=0,smax_value=4294967296 (0x100000000),umin_value=0,umax_value=0x100000000,var_off=(0x0; 0x100000000),s32_min_value=0,s32_max_value=0,u32_min_value=0,u32_max_value=0) R3_w=inv4294967298 R10=fp0 [...] Fixes: 3f50f132d840 ("bpf: Verifier, do explicit ALU32 bounds tracking") Fixes: 2921c90d4718 ("bpf: Fix a verifier failure with xor") Reported-by: Manfred Paul (@_manfp) Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Reviewed-by: John Fastabend <john.fastabend@gmail.com> Acked-by: Alexei Starovoitov <ast@kernel.org>
| | * bpf: Forbid trampoline attach for functions with variable argumentsJiri Olsa2021-05-071-0/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | We can't currently allow to attach functions with variable arguments. The problem is that we should save all the registers for arguments, which is probably doable, but if caller uses more than 6 arguments, we need stack data, which will be wrong, because of the extra stack frame we do in bpf trampoline, so we could crash. Also currently there's malformed trampoline code generated for such functions at the moment as described in: https://lore.kernel.org/bpf/20210429212834.82621-1-jolsa@kernel.org/ Signed-off-by: Jiri Olsa <jolsa@kernel.org> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Andrii Nakryiko <andrii@kernel.org> Link: https://lore.kernel.org/bpf/20210505132529.401047-1-jolsa@kernel.org
* | | Merge branch 'for-5.13-fixes' of ↵Linus Torvalds2021-05-245-16/+13
|\ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup fixes from Tejun Heo: - "cgroup_disable=" boot param was being applied too late confusing some subsystems. Fix it by moving application to __setup() time. - Comment spelling fixes. Included here to lower the chance of trivial future merge conflicts. * 'for-5.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: fix spelling mistakes cgroup: disable controllers at parse time
| * | | cgroup: fix spelling mistakesZhen Lei2021-05-245-8/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix some spelling mistakes in comments: hierarhcy ==> hierarchy automtically ==> automatically overriden ==> overridden In absense of .. or ==> In absence of .. and assocaited ==> associated taget ==> target initate ==> initiate succeded ==> succeeded curremt ==> current udpated ==> updated Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
| * | | cgroup: disable controllers at parse timeShakeel Butt2021-05-201-8/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch effectively reverts the commit a3e72739b7a7 ("cgroup: fix too early usage of static_branch_disable()"). The commit 6041186a3258 ("init: initialize jump labels before command line option parsing") has moved the jump_label_init() before parse_args() which has made the commit a3e72739b7a7 unnecessary. On the other hand there are consequences of disabling the controllers later as there are subsystems doing the controller checks for different decisions. One such incident is reported [1] regarding the memory controller and its impact on memory reclaim code. [1] https://lore.kernel.org/linux-mm/921e53f3-4b13-aab8-4a9e-e83ff15371e4@nec.com Signed-off-by: Shakeel Butt <shakeelb@google.com> Reported-by: NOMURA JUNICHI(野村　淳一) <junichi.nomura@nec.com> Signed-off-by: Tejun Heo <tj@kernel.org> Tested-by: Jun'ichi Nomura <junichi.nomura@nec.com>
* | | | Merge branch 'for-5.13-fixes' of ↵Linus Torvalds2021-05-241-2/+10
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq Pull workqueue fix from Tejun Heo: "One commit to fix spurious workqueue stall warnings across VM suspensions" * 'for-5.13-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq: wq: handle VM suspension in stall detection
| * | | | wq: handle VM suspension in stall detectionSergey Senozhatsky2021-05-201-2/+10
| |/ / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If VCPU is suspended (VM suspend) in wq_watchdog_timer_fn() then once this VCPU resumes it will see the new jiffies value, while it may take a while before IRQ detects PVCLOCK_GUEST_STOPPED on this VCPU and updates all the watchdogs via pvclock_touch_watchdogs(). There is a small chance of misreported WQ stalls in the meantime, because new jiffies is time_after() old 'ts + thresh'. wq_watchdog_timer_fn() { for_each_pool(pool, pi) { if (time_after(jiffies, ts + thresh)) { pr_emerg("BUG: workqueue lockup - pool"); } } } Save jiffies at the beginning of this function and use that value for stall detection. If VM gets suspended then we continue using "old" jiffies value and old WQ touch timestamps. If IRQ at some point restarts the stall detection cycle (pvclock_touch_watchdogs()) then old jiffies will always be before new 'ts + thresh'. Signed-off-by: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by: Tejun Heo <tj@kernel.org>
* | | | Merge tag 'locking-urgent-2021-05-23' of ↵Linus Torvalds2021-05-235-13/+19
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking fixes from Thomas Gleixner: "Two locking fixes: - Invoke the lockdep tracepoints in the correct place so the ordering is correct again - Don't leave the mutex WAITER bit stale when the last waiter is dropping out early due to a signal as that forces all subsequent lock operations needlessly into the slowpath until it's cleaned up again" * tag 'locking-urgent-2021-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signal locking/lockdep: Correct calling tracepoints
| * | | | locking/mutex: clear MUTEX_FLAGS if wait_list is empty due to signalZqiang2021-05-184-11/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When a interruptible mutex locker is interrupted by a signal without acquiring this lock and removed from the wait queue. if the mutex isn't contended enough to have a waiter put into the wait queue again, the setting of the WAITER bit will force mutex locker to go into the slowpath to acquire the lock every time, so if the wait queue is empty, the WAITER bit need to be clear. Fixes: 040a0a371005 ("mutex: Add support for wound/wait style locks") Suggested-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Zqiang <qiang.zhang@windriver.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210517034005.30828-1-qiang.zhang@windriver.com
| * | | | locking/lockdep: Correct calling tracepointsLeo Yan2021-05-181-2/+2
| |/ / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The commit eb1f00237aca ("lockdep,trace: Expose tracepoints") reverses tracepoints for lock_contended() and lock_acquired(), thus the ftrace log shows the wrong locking sequence that "acquired" event is prior to "contended" event: <idle>-0 [001] d.s3 20803.501685: lock_acquire: 0000000008b91ab4 &sg_policy->update_lock <idle>-0 [001] d.s3 20803.501686: lock_acquired: 0000000008b91ab4 &sg_policy->update_lock <idle>-0 [001] d.s3 20803.501689: lock_contended: 0000000008b91ab4 &sg_policy->update_lock <idle>-0 [001] d.s3 20803.501690: lock_release: 0000000008b91ab4 &sg_policy->update_lock This patch fixes calling tracepoints for lock_contended() and lock_acquired(). Fixes: eb1f00237aca ("lockdep,trace: Expose tracepoints") Signed-off-by: Leo Yan <leo.yan@linaro.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210512120937.90211-1-leo.yan@linaro.org
* | | | watchdog: reliable handling of timestampsPetr Mladek2021-05-221-14/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 9bf3bc949f8a ("watchdog: cleanup handling of false positives") tried to handle a virtual host stopped by the host a more straightforward and cleaner way. But it introduced a risk of false softlockup reports. The virtual host might be stopped at any time, for example between kvm_check_and_clear_guest_paused() and is_softlockup(). As a result, is_softlockup() might read the updated jiffies and detects a softlockup. A solution might be to put back kvm_check_and_clear_guest_paused() after is_softlockup() and detect it. But it would put back the cycle that complicates the logic. In fact, the handling of all the timestamps is not reliable. The code does not guarantee when and how many times the timestamps are read. For example, "period_ts" might be touched anytime also from NMI and re-read in is_softlockup(). It works just by chance. Fix all the problems by making the code even more explicit. 1. Make sure that "now" and "period_ts" timestamps are read only once. They might be changed at anytime by NMI or when the virtual guest is stopped by the host. Note that "now" timestamp does this implicitly because "jiffies" is marked volatile. 2. "now" time must be read first. The state of "period_ts" will decide whether it will be used or the period will get restarted. 3. kvm_check_and_clear_guest_paused() must be called before reading "period_ts". It touches the variable when the guest was stopped. As a result, "now" timestamp is used only when the watchdog was not touched and the guest not stopped in the meantime. "period_ts" is restarted in all other situations. Link: https://lkml.kernel.org/r/YKT55gw+RZfyoFf7@alley Fixes: 9bf3bc949f8aeefeacea4b ("watchdog: cleanup handling of false positives") Signed-off-by: Petr Mladek <pmladek@suse.com> Reported-by: Sergey Senozhatsky <senozhatsky@chromium.org> Reviewed-by: Sergey Senozhatsky <senozhatsky@chromium.org> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | | Merge branch 'for-v5.13-rc3' of ↵Linus Torvalds2021-05-212-34/+36
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull siginfo fix from Eric Biederman: "During the merge window an issue with si_perf and the siginfo ABI came up. The alpha and sparc siginfo structure layout had changed with the addition of SIGTRAP TRAP_PERF and the new field si_perf. The reason only alpha and sparc were affected is that they are the only architectures that use si_trapno. Looking deeper it was discovered that si_trapno is used for only a few select signals on alpha and sparc, and that none of the other _sigfault fields past si_addr are used at all. Which means technically no regression on alpha and sparc. While the alignment concerns might be dismissed the abuse of si_errno by SIGTRAP TRAP_PERF does have the potential to cause regressions in existing userspace. While we still have time before userspace starts using and depending on the new definition siginfo for SIGTRAP TRAP_PERF this set of changes cleans up siginfo_t. - The si_trapno field is demoted from magic alpha and sparc status and made an ordinary union member of the _sigfault member of siginfo_t. Without moving it of course. - si_perf is replaced with si_perf_data and si_perf_type ending the abuse of si_errno. - Unnecessary additions to signalfd_siginfo are removed" * 'for-v5.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: signalfd: Remove SIL_PERF_EVENT fields from signalfd_siginfo signal: Deliver all of the siginfo perf data in _perf signal: Factor force_sig_perf out of perf_sigtrap signal: Implement SIL_FAULT_TRAPNO siginfo: Move si_trapno inside the union inside _si_fault
| * | | | signal: Deliver all of the siginfo perf data in _perfEric W. Biederman2021-05-181-8/+13
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Don't abuse si_errno and deliver all of the perf data in _perf member of siginfo_t. Note: The data field in the perf data structures in a u64 to allow a pointer to be encoded without needed to implement a 32bit and 64bit version of the same structure. There already exists a 32bit and 64bit versions siginfo_t, and the 32bit version can not include a 64bit member as it only has 32bit alignment. So unsigned long is used in siginfo_t instead of a u64 as unsigned long can encode a pointer on all architectures linux supports. v1: https://lkml.kernel.org/r/m11rarqqx2.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210503203814.25487-10-ebiederm@xmission.com v3: https://lkml.kernel.org/r/20210505141101.11519-11-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-4-ebiederm@xmission.com Reviewed-by: Marco Elver <elver@google.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * | | | signal: Factor force_sig_perf out of perf_sigtrapEric W. Biederman2021-05-182-9/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Separate filling in siginfo for TRAP_PERF from deciding that siginal needs to be sent. There are enough little details that need to be correct when properly filling in siginfo_t that it is easy to make mistakes if filling in the siginfo_t is in the same function with other logic. So factor out force_sig_perf to reduce the cognative load of on reviewers, maintainers and implementors. v1: https://lkml.kernel.org/r/m17dkjqqxz.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210505141101.11519-10-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-3-ebiederm@xmission.com Reviewed-by: Marco Elver <elver@google.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * | | | signal: Implement SIL_FAULT_TRAPNOEric W. Biederman2021-05-181-22/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Now that si_trapno is part of the union in _si_fault and available on all architectures, add SIL_FAULT_TRAPNO and update siginfo_layout to return SIL_FAULT_TRAPNO when the code assumes si_trapno is valid. There is room for future changes to reduce when si_trapno is valid but this is all that is needed to make si_trapno and the other members of the the union in _sigfault mutually exclusive. Update the code that uses siginfo_layout to deal with SIL_FAULT_TRAPNO and have the same code ignore si_trapno in in all other cases. v1: https://lkml.kernel.org/r/m1o8dvs7s7.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210505141101.11519-6-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-2-ebiederm@xmission.com Reviewed-by: Marco Elver <elver@google.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
| * | | | siginfo: Move si_trapno inside the union inside _si_faultEric W. Biederman2021-05-181-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It turns out that linux uses si_trapno very sparingly, and as such it can be considered extra information for a very narrow selection of signals, rather than information that is present with every fault reported in siginfo. As such move si_trapno inside the union inside of _si_fault. This results in no change in placement, and makes it eaiser to extend _si_fault in the future as this reduces the number of special cases. In particular with si_trapno included in the union it is no longer a concern that the union must be pointer aligned on most architectures because the union follows immediately after si_addr which is a pointer. This change results in a difference in siginfo field placement on sparc and alpha for the fields si_addr_lsb, si_lower, si_upper, si_pkey, and si_perf. These architectures do not implement the signals that would use si_addr_lsb, si_lower, si_upper, si_pkey, and si_perf. Further these architecture have not yet implemented the userspace that would use si_perf. The point of this change is in fact to correct these placement issues before sparc or alpha grow userspace that cares. This change was discussed[1] and the agreement is that this change is currently safe. [1]: https://lkml.kernel.org/r/CAK8P3a0+uKYwL1NhY6Hvtieghba2hKYGD6hcKx5n8=4Gtt+pHA@mail.gmail.com Acked-by: Marco Elver <elver@google.com> v1: https://lkml.kernel.org/r/m1tunns7yf.fsf_-_@fess.ebiederm.org v2: https://lkml.kernel.org/r/20210505141101.11519-5-ebiederm@xmission.com Link: https://lkml.kernel.org/r/20210517195748.8880-1-ebiederm@xmission.com Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | | | | Merge tag 'modules-for-v5.13-rc3' of ↵Linus Torvalds2021-05-211-6/+11
|\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux Pull module fix from Jessica Yu: "When CONFIG_MODULE_UNLOAD=n, module exit sections get sorted into the init region of the module in order to satisfy the requirements of jump_labels and static_calls. Previously, the exit section check was done in module_init_section(), but the solution there is not completely arch-indepedent as ARM is a special case and supplies its own module_init_section() function. Instead of pushing this logic further to the arch-specific code, switch to an arch-independent solution to check for module exit sections in the core module loader code in layout_sections() instead" * tag 'modules-for-v5.13-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux: module: check for exit sections in layout_sections() instead of module_init_section()
| * | | | | module: check for exit sections in layout_sections() instead of ↵Jessica Yu2021-05-171-6/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | module_init_section() Previously, when CONFIG_MODULE_UNLOAD=n, the module loader just does not attempt to load exit sections since it never expects that any code in those sections will ever execute. However, dynamic code patching (alternatives, jump_label and static_call) can have sites in __exit code, even if __exit is never executed. Therefore __exit must be present at runtime, at least for as long as __init code is. Commit 33121347fb1c ("module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD") solves the requirements of jump_labels and static_calls by putting the exit sections in the init region of the module so that they are at least present at init, and discarded afterwards. It does this by including a check for exit sections in module_init_section(), so that it also returns true for exit sections, and the module loader will automatically sort them in the init region of the module. However, the solution there was not completely arch-independent. ARM is a special case where it supplies its own module_{init, exit}_section() functions. Instead of pushing the exit section checks into module_init_section(), just implement the exit section check in layout_sections(), so that we don't have to touch arch-dependent code. Fixes: 33121347fb1c ("module: treat exit sections the same as init sections when !CONFIG_MODULE_UNLOAD") Reviewed-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> Signed-off-by: Jessica Yu <jeyu@kernel.org>
* | | | | | Merge branch 'urgent.2021.05.20a' of ↵Linus Torvalds2021-05-201-1/+2
|\ \ \ \ \ \ | |_|_|/ / / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu Pull kcsan fix from Paul McKenney: "Fix for a regression introduced in this merge window by commit e36299efe7d7 ("kcsan, debugfs: Move debugfs file creation out of early init"). The regression is not easy to trigger, requiring a KCSAN build using clang with CONFIG_LTO_CLANG=y. The fix is to simply make the kcsan_debugfs_init() function's type initcall-compatible. This has been posted to the relevant mailing lists:" * 'urgent.2021.05.20a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu: kcsan: Fix debugfs initcall return type
| * | | | | kcsan: Fix debugfs initcall return typeArnd Bergmann2021-05-181-1/+2
| |/ / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | clang with CONFIG_LTO_CLANG points out that an initcall function should return an 'int' due to the changes made to the initcall macros in commit 3578ad11f3fb ("init: lto: fix PREL32 relocations"): kernel/kcsan/debugfs.c:274:15: error: returning 'void' from a function with incompatible result type 'int' late_initcall(kcsan_debugfs_init); ~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~ include/linux/init.h:292:46: note: expanded from macro 'late_initcall' #define late_initcall(fn) __define_initcall(fn, 7) Fixes: e36299efe7d7 ("kcsan, debugfs: Move debugfs file creation out of early init") Cc: stable <stable@vger.kernel.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Marco Elver <elver@google.com> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Reviewed-by: Miguel Ojeda <ojeda@kernel.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | | | | Merge tag 'timers-urgent-2021-05-16' of ↵Linus Torvalds2021-05-161-1/+1
|\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer fixes from Thomas Gleixner: "Two fixes for timers: - Use the ALARM feature check in the alarmtimer core code insted of the old method of checking for the set_alarm() callback. Drivers can have that callback set but the feature bit cleared. If such a RTC device is selected then alarms wont work. - Use a proper define to let the preprocessor check whether Hyper-V VDSO clocksource should be active. The code used a constant in an enum with #ifdef, which evaluates to always false and disabled the clocksource for VDSO" * tag 'timers-urgent-2021-05-16' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: clocksource/drivers/hyper-v: Re-enable VDSO_CLOCKMODE_HVCLOCK on X86 alarmtimer: Check RTC features instead of ops
| * | | | | alarmtimer: Check RTC features instead of opsAlexandre Belloni2021-05-111-1/+1
| |/ / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | RTC drivers used to leave .set_alarm() NULL in order to signal the RTC device doesn't support alarms. The drivers are now clearing the RTC_FEATURE_ALARM bit for that purpose in order to keep the rtc_class_ops structure const. So now, .set_alarm() is set unconditionally and this possibly causes the alarmtimer code to select an RTC device that doesn't support alarms. Test RTC_FEATURE_ALARM instead of relying on ops->set_alarm to determine whether alarms are available. Fixes: 7ae41220ef58 ("rtc: introduce features bitfield") Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20210511014516.563031-1-alexandre.belloni@bootlin.com
* | | | | Merge tag 'sched-urgent-2021-05-15' of ↵Linus Torvalds2021-05-151-1/+1
|\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Ingo Molnar: "Fix an idle CPU selection bug, and an AMD Ryzen maximum frequency enumeration bug" * tag 'sched-urgent-2021-05-15' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86, sched: Fix the AMD CPPC maximum performance value on certain AMD Ryzen generations sched/fair: Fix clearing of has_idle_cores flag in select_idle_cpu()
| * | | | | sched/fair: Fix clearing of has_idle_cores flag in select_idle_cpu()Gautham R. Shenoy2021-05-121-1/+1
| |/ / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In commit: 9fe1f127b913 ("sched/fair: Merge select_idle_core/cpu()") in select_idle_cpu(), we check if an idle core is present in the LLC of the target CPU via the flag "has_idle_cores". We look for the idle core in select_idle_cores(). If select_idle_cores() isn't able to find an idle core/CPU, we need to unset the has_idle_cores flag in the LLC of the target to prevent other CPUs from going down this route. However, the current code is unsetting it in the LLC of the current CPU instead of the target CPU. This patch fixes this issue. Fixes: 9fe1f127b913 ("sched/fair: Merge select_idle_core/cpu()") Signed-off-by: Gautham R. Shenoy <ego@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@techsingularity.net> Link: https://lore.kernel.org/r/1620746169-13996-1-git-send-email-ego@linux.vnet.ibm.com
* | | | | Merge branch 'akpm' (patches from Andrew)Linus Torvalds2021-05-151-1/+1
|\ \ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Merge misc fixes from Andrew Morton: "13 patches. Subsystems affected by this patch series: resource, squashfs, hfsplus, modprobe, and mm (hugetlb, slub, userfaultfd, ksm, pagealloc, kasan, pagemap, and ioremap)" * emailed patches from Andrew Morton <akpm@linux-foundation.org>: mm/ioremap: fix iomap_max_page_shift docs: admin-guide: update description for kernel.modprobe sysctl hfsplus: prevent corruption in shrinking truncate mm/filemap: fix readahead return types kasan: fix unit tests with CONFIG_UBSAN_LOCAL_BOUNDS enabled mm: fix struct page layout on 32-bit systems ksm: revert "use GET_KSM_PAGE_NOLOCK to get ksm page in remove_rmap_item_from_tree()" userfaultfd: release page in error path to avoid BUG_ON squashfs: fix divide error in calculate_skip() kernel/resource: fix return code check in __request_free_mem_region mm, slub: move slub_debug static key enabling outside slab_mutex mm/hugetlb: fix cow where page writtable in child mm/hugetlb: fix F_SEAL_FUTURE_WRITE
| * | | | | kernel/resource: fix return code check in __request_free_mem_regionAlistair Popple2021-05-141-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Splitting an earlier version of a patch that allowed calling __request_region() while holding the resource lock into a series of patches required changing the return code for the newly introduced __request_region_locked(). Unfortunately this change was not carried through to a subsequent commit 56fd94919b8b ("kernel/resource: fix locking in request_free_mem_region") in the series. This resulted in a use-after-free due to freeing the struct resource without properly releasing it. Fix this by correcting the return code check so that the struct is not freed if the request to add it was successful. Link: https://lkml.kernel.org/r/20210512073528.22334-1-apopple@nvidia.com Fixes: 56fd94919b8b ("kernel/resource: fix locking in request_free_mem_region") Signed-off-by: Alistair Popple <apopple@nvidia.com> Reported-by: kernel test robot <oliver.sang@intel.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Daniel Vetter <daniel.vetter@ffwll.ch> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Jerome Glisse <jglisse@redhat.com> Cc: John Hubbard <jhubbard@nvidia.com> Cc: Muchun Song <smuchun@gmail.com> Cc: Oliver Sang <oliver.sang@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | | | | Merge tag 'trace-v5.13-rc1' of ↵Linus Torvalds2021-05-141-4/+27
|\ \ \ \ \ \ | |/ / / / / |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace Pull tracing fix from Steven Rostedt: "Fix trace_check_vprintf() for %.*s The sanity check of all strings being read from the ring buffer to make sure they are in safe memory space did not account for the %.*s notation having another parameter to process (the length). Add that to the check" * tag 'trace-v5.13-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: tracing: Handle %.*s in trace_check_vprintf()
| * | | | | tracing: Handle %.*s in trace_check_vprintf()Steven Rostedt (VMware)2021-05-131-4/+27
| |/ / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If a trace event uses the %*.s notation, the trace_check_vprintf() will fail and will warn about a bad processing of strings, because it does not take into account the length field when processing the star (*) part. Have it handle this case as well. Link: https://lore.kernel.org/linux-nfs/238C0E2D-C2A4-4578-ADD2-C565B3B99842@oracle.com/ Reported-by: Chuck Lever III <chuck.lever@oracle.com> Fixes: 9a6944fee68e2 ("tracing: Add a verifier to check string pointers for trace events") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
* / / / / ptrace: make ptrace() fail if the tracee changed its pid unexpectedlyOleg Nesterov2021-05-121-1/+17
|/ / / / | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Suppose we have 2 threads, the group-leader L and a sub-theread T, both parked in ptrace_stop(). Debugger tries to resume both threads and does ptrace(PTRACE_CONT, T); ptrace(PTRACE_CONT, L); If the sub-thread T execs in between, the 2nd PTRACE_CONT doesn not resume the old leader L, it resumes the post-exec thread T which was actually now stopped in PTHREAD_EVENT_EXEC. In this case the PTHREAD_EVENT_EXEC event is lost, and the tracer can't know that the tracee changed its pid. This patch makes ptrace() fail in this case until debugger does wait() and consumes PTHREAD_EVENT_EXEC which reports old_pid. This affects all ptrace requests except the "asynchronous" PTRACE_INTERRUPT/KILL. The patch doesn't add the new PTRACE_ option to not complicate the API, and I _hope_ this won't cause any noticeable regression: - If debugger uses PTRACE_O_TRACEEXEC and the thread did an exec and the tracer does a ptrace request without having consumed the exec event, it's 100% sure that the thread the ptracer thinks it is targeting does not exist anymore, or isn't the same as the one it thinks it is targeting. - To some degree this patch adds nothing new. In the scenario above ptrace(L) can fail with -ESRCH if it is called after the execing sub-thread wakes the leader up and before it "steals" the leader's pid. Test-case: #include <stdio.h> #include <unistd.h> #include <signal.h> #include <sys/ptrace.h> #include <sys/wait.h> #include <errno.h> #include <pthread.h> #include <assert.h> void *tf(void *arg) { execve("/usr/bin/true", NULL, NULL); assert(0); return NULL; } int main(void) { int leader = fork(); if (!leader) { kill(getpid(), SIGSTOP); pthread_t th; pthread_create(&th, NULL, tf, NULL); for (;;) pause(); return 0; } waitpid(leader, NULL, WSTOPPED); ptrace(PTRACE_SEIZE, leader, 0, PTRACE_O_TRACECLONE | PTRACE_O_TRACEEXEC); waitpid(leader, NULL, 0); ptrace(PTRACE_CONT, leader, 0,0); waitpid(leader, NULL, 0); int status, thread = waitpid(-1, &status, 0); assert(thread > 0 && thread != leader); assert(status == 0x80137f); ptrace(PTRACE_CONT, thread, 0,0); /* * waitid() because waitpid(leader, &status, WNOWAIT) does not * report status. Why ???? * * Why WEXITED? because we have another kernel problem connected * to mt-exec. */ siginfo_t info; assert(waitid(P_PID, leader, &info, WSTOPPED|WEXITED|WNOWAIT) == 0); assert(info.si_pid == leader && info.si_status == 0x0405); /* OK, it sleeps in ptrace(PTRACE_EVENT_EXEC == 0x04) */ assert(ptrace(PTRACE_CONT, leader, 0,0) == -1); assert(errno == ESRCH); assert(leader == waitpid(leader, &status, WNOHANG)); assert(status == 0x04057f); assert(ptrace(PTRACE_CONT, leader, 0,0) == 0); return 0; } Signed-off-by: Oleg Nesterov <oleg@redhat.com> Reported-by: Simon Marchi <simon.marchi@efficios.com> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Acked-by: Pedro Alves <palves@redhat.com> Acked-by: Simon Marchi <simon.marchi@efficios.com> Acked-by: Jan Kratochvil <jan.kratochvil@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* | | | Merge tag 'sched-urgent-2021-05-09' of ↵Linus Torvalds2021-05-093-14/+36
|\ \ \ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull scheduler fixes from Thomas Gleixner: "A set of scheduler updates: - Prevent PSI state corruption when schedule() races with cgroup move. A recent commit combined two PSI callbacks to reduce the number of cgroup tree updates, but missed that schedule() can drop rq::lock for load balancing, which opens the race window for cgroup_move_task() which then observes half updated state. The fix is to solely use task::ps_flags instead of looking at the potentially mismatching scheduler state - Prevent an out-of-bounds access in uclamp caused bu a rounding division which can lead to an off-by-one error exceeding the buckets array size. - Prevent unfairness caused by missing load decay when a task is attached to a cfs runqueue. The old load of the task was attached to the runqueue and never removed. Fix it by enforcing the load update through the hierarchy for unthrottled run queue instances. - A documentation fix fot the 'sched_verbose' command line option" * tag 'sched-urgent-2021-05-09' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/fair: Fix unfairness caused by missing load decay sched: Fix out-of-bound access in uclamp psi: Fix psi state corruption when schedule() races with cgroup move sched,doc: sched_debug_verbose cmdline should be sched_verbose
| * | | | sched/fair: Fix unfairness caused by missing load decayOdin Ugedal2021-05-061-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This fixes an issue where old load on a cfs_rq is not properly decayed, resulting in strange behavior where fairness can decrease drastically. Real workloads with equally weighted control groups have ended up getting a respective 99% and 1%(!!) of cpu time. When an idle task is attached to a cfs_rq by attaching a pid to a cgroup, the old load of the task is attached to the new cfs_rq and sched_entity by attach_entity_cfs_rq. If the task is then moved to another cpu (and therefore cfs_rq) before being enqueued/woken up, the load will be moved to cfs_rq->removed from the sched_entity. Such a move will happen when enforcing a cpuset on the task (eg. via a cgroup) that force it to move. The load will however not be removed from the task_group itself, making it look like there is a constant load on that cfs_rq. This causes the vruntime of tasks on other sibling cfs_rq's to increase faster than they are supposed to; causing severe fairness issues. If no other task is started on the given cfs_rq, and due to the cpuset it would not happen, this load would never be properly unloaded. With this patch the load will be properly removed inside update_blocked_averages. This also applies to tasks moved to the fair scheduling class and moved to another cpu, and this path will also fix that. For fork, the entity is queued right away, so this problem does not affect that. This applies to cases where the new process is the first in the cfs_rq, issue introduced 3d30544f0212 ("sched/fair: Apply more PELT fixes"), and when there has previously been load on the cgroup but the cgroup was removed from the leaflist due to having null PELT load, indroduced in 039ae8bcf7a5 ("sched/fair: Fix O(nr_cgroups) in the load balancing path"). For a simple cgroup hierarchy (as seen below) with two equally weighted groups, that in theory should get 50/50 of cpu time each, it often leads to a load of 60/40 or 70/30. parent/ cg-1/ cpu.weight: 100 cpuset.cpus: 1 cg-2/ cpu.weight: 100 cpuset.cpus: 1 If the hierarchy is deeper (as seen below), while keeping cg-1 and cg-2 equally weighted, they should still get a 50/50 balance of cpu time. This however sometimes results in a balance of 10/90 or 1/99(!!) between the task groups. $ ps u -C stress USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND root 18568 1.1 0.0 3684 100 pts/12 R+ 13:36 0:00 stress --cpu 1 root 18580 99.3 0.0 3684 100 pts/12 R+ 13:36 0:09 stress --cpu 1 parent/ cg-1/ cpu.weight: 100 sub-group/ cpu.weight: 1 cpuset.cpus: 1 cg-2/ cpu.weight: 100 sub-group/ cpu.weight: 10000 cpuset.cpus: 1 This can be reproduced by attaching an idle process to a cgroup and moving it to a given cpuset before it wakes up. The issue is evident in many (if not most) container runtimes, and has been reproduced with both crun and runc (and therefore docker and all its "derivatives"), and with both cgroup v1 and v2. Fixes: 3d30544f0212 ("sched/fair: Apply more PELT fixes") Fixes: 039ae8bcf7a5 ("sched/fair: Fix O(nr_cgroups) in the load balancing path") Signed-off-by: Odin Ugedal <odin@uged.al> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Link: https://lkml.kernel.org/r/20210501141950.23622-2-odin@uged.al
| * | | | sched: Fix out-of-bound access in uclampQuentin Perret2021-05-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Util-clamp places tasks in different buckets based on their clamp values for performance reasons. However, the size of buckets is currently computed using a rounding division, which can lead to an off-by-one error in some configurations. For instance, with 20 buckets, the bucket size will be 1024/20=51. A task with a clamp of 1024 will be mapped to bucket id 1024/51=20. Sadly, correct indexes are in range [0,19], hence leading to an out of bound memory access. Clamp the bucket id to fix the issue. Fixes: 69842cba9ace ("sched/uclamp: Add CPU's clamp buckets refcounting") Suggested-by: Qais Yousef <qais.yousef@arm.com> Signed-off-by: Quentin Perret <qperret@google.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org> Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lkml.kernel.org/r/20210430151412.160913-1-qperret@google.com
| * | | | psi: Fix psi state corruption when schedule() races with cgroup moveJohannes Weiner2021-05-061-10/+26
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 4117cebf1a9f ("psi: Optimize task switch inside shared cgroups") introduced a race condition that corrupts internal psi state. This manifests as kernel warnings, sometimes followed by bogusly high IO pressure: psi: task underflow! cpu=1 t=2 tasks=[0 0 0 0] clear=c set=0 (schedule() decreasing RUNNING and ONCPU, both of which are 0) psi: incosistent task state! task=2412744:systemd cpu=17 psi_flags=e clear=3 set=0 (cgroup_move_task() clearing MEMSTALL and IOWAIT, but task is MEMSTALL | RUNNING | ONCPU) What the offending commit does is batch the two psi callbacks in schedule() to reduce the number of cgroup tree updates. When prev is deactivated and removed from the runqueue, nothing is done in psi at first; when the task switch completes, TSK_RUNNING and TSK_IOWAIT are updated along with TSK_ONCPU. However, the deactivation and the task switch inside schedule() aren't atomic: pick_next_task() may drop the rq lock for load balancing. When this happens, cgroup_move_task() can run after the task has been physically dequeued, but the psi updates are still pending. Since it looks at the task's scheduler state, it doesn't move everything to the new cgroup that the task switch that follows is about to clear from it. cgroup_move_task() will leak the TSK_RUNNING count in the old cgroup, and psi_sched_switch() will underflow it in the new cgroup. A similar thing can happen for iowait. TSK_IOWAIT is usually set when a p->in_iowait task is dequeued, but again this update is deferred to the switch. cgroup_move_task() can see an unqueued p->in_iowait task and move a non-existent TSK_IOWAIT. This results in the inconsistent task state warning, as well as a counter underflow that will result in permanent IO ghost pressure being reported. Fix this bug by making cgroup_move_task() use task->psi_flags instead of looking at the potentially mismatching scheduler state. [ We used the scheduler state historically in order to not rely on task->psi_flags for anything but debugging. But that ship has sailed anyway, and this is simpler and more robust. We previously already batched TSK_ONCPU clearing with the TSK_RUNNING update inside the deactivation call from schedule(). But that ordering was safe and didn't result in TSK_ONCPU corruption: unlike most places in the scheduler, cgroup_move_task() only checked task_current() and handled TSK_ONCPU if the task was still queued. ] Fixes: 4117cebf1a9f ("psi: Optimize task switch inside shared cgroups") Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20210503174917.38579-1-hannes@cmpxchg.org
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-22 23:16:51 +0000