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* exit: Fix Sparse errors and warningsMadhuparna Bhowmik2020-02-281-2/+2
| | | | | | | | | | | | | | | This patch fixes the following sparse error: kernel/exit.c:627:25: error: incompatible types in comparison expression And the following warning: kernel/exit.c:626:40: warning: incorrect type in assignment Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> Acked-by: Oleg Nesterov <oleg@redhat.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> [christian.brauner@ubuntu.com: edit commit message] Link: https://lore.kernel.org/r/20200130062028.4870-1-madhuparnabhowmik10@gmail.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
* Merge tag 'for-linus-2020-01-03' of ↵Linus Torvalds2020-01-031-4/+8
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull thread fixes from Christian Brauner: "Here are two fixes: - Panic earlier when global init exits to generate useable coredumps. Currently, when global init and all threads in its thread-group have exited we panic via: do_exit() -> exit_notify() -> forget_original_parent() -> find_child_reaper() This makes it hard to extract a useable coredump for global init from a kernel crashdump because by the time we panic exit_mm() will have already released global init's mm. We now panic slightly earlier. This has been a problem in certain environments such as Android. - Fix a race in assigning and reading taskstats for thread-groups with more than one thread. This patch has been waiting for quite a while since people disagreed on what the correct fix was at first" * tag 'for-linus-2020-01-03' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: exit: panic before exit_mm() on global init exit taskstats: fix data-race
| * exit: panic before exit_mm() on global init exitchenqiwu2019-12-211-4/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently, when global init and all threads in its thread-group have exited we panic via: do_exit() -> exit_notify() -> forget_original_parent() -> find_child_reaper() This makes it hard to extract a useable coredump for global init from a kernel crashdump because by the time we panic exit_mm() will have already released global init's mm. This patch moves the panic futher up before exit_mm() is called. As was the case previously, we only panic when global init and all its threads in the thread-group have exited. Signed-off-by: chenqiwu <chenqiwu@xiaomi.com> Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Oleg Nesterov <oleg@redhat.com> [christian.brauner@ubuntu.com: fix typo, rewrite commit message] Link: https://lore.kernel.org/r/1576736993-10121-1-git-send-email-qiwuchen55@gmail.com Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
* | Merge tag 'notifications-pipe-prep-20191115' of ↵Linus Torvalds2019-11-301-1/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs Pull pipe rework from David Howells: "This is my set of preparatory patches for building a general notification queue on top of pipes. It makes a number of significant changes: - It removes the nr_exclusive argument from __wake_up_sync_key() as this is always 1. This prepares for the next step: - Adds wake_up_interruptible_sync_poll_locked() so that poll can be woken up from a function that's holding the poll waitqueue spinlock. - Change the pipe buffer ring to be managed in terms of unbounded head and tail indices rather than bounded index and length. This means that reading the pipe only needs to modify one index, not two. - A selection of helper functions are provided to query the state of the pipe buffer, plus a couple to apply updates to the pipe indices. - The pipe ring is allowed to have kernel-reserved slots. This allows many notification messages to be spliced in by the kernel without allowing userspace to pin too many pages if it writes to the same pipe. - Advance the head and tail indices inside the pipe waitqueue lock and use wake_up_interruptible_sync_poll_locked() to poke poll without having to take the lock twice. - Rearrange pipe_write() to preallocate the buffer it is going to write into and then drop the spinlock. This allows kernel notifications to then be added the ring whilst it is filling the buffer it allocated. The read side is stalled because the pipe mutex is still held. - Don't wake up readers on a pipe if there was already data in it when we added more. - Don't wake up writers on a pipe if the ring wasn't full before we removed a buffer" * tag 'notifications-pipe-prep-20191115' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs: pipe: Remove sync on wake_ups pipe: Increase the writer-wakeup threshold to reduce context-switch count pipe: Check for ring full inside of the spinlock in pipe_write() pipe: Remove redundant wakeup from pipe_write() pipe: Rearrange sequence in pipe_write() to preallocate slot pipe: Conditionalise wakeup in pipe_read() pipe: Advance tail pointer inside of wait spinlock in pipe_read() pipe: Allow pipes to have kernel-reserved slots pipe: Use head and tail pointers for the ring, not cursor and length Add wake_up_interruptible_sync_poll_locked() Remove the nr_exclusive argument from __wake_up_sync_key() pipe: Reduce #inclusion of pipe_fs_i.h
| * | Remove the nr_exclusive argument from __wake_up_sync_key()David Howells2019-10-231-1/+1
| |/ | | | | | | | | | | | | | | | | Remove the nr_exclusive argument from __wake_up_sync_key() and derived functions as everything seems to set it to 1. Note also that if it wasn't set to 1, it would clear WF_SYNC anyway. Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
* | Merge branch 'locking-core-for-linus' of ↵Linus Torvalds2019-11-261-28/+2
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - A comprehensive rewrite of the robust/PI futex code's exit handling to fix various exit races. (Thomas Gleixner et al) - Rework the generic REFCOUNT_FULL implementation using atomic_fetch_* operations so that the performance impact of the cmpxchg() loops is mitigated for common refcount operations. With these performance improvements the generic implementation of refcount_t should be good enough for everybody - and this got confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and REFCOUNT_FULL entirely, leaving the generic implementation enabled unconditionally. (Will Deacon) - Other misc changes, fixes, cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits) lkdtm: Remove references to CONFIG_REFCOUNT_FULL locking/refcount: Remove unused 'refcount_error_report()' function locking/refcount: Consolidate implementations of refcount_t locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions locking/refcount: Move saturation warnings out of line locking/refcount: Improve performance of generic REFCOUNT_FULL code locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header locking/refcount: Remove unused refcount_*_checked() variants locking/refcount: Ensure integer operands are treated as signed locking/refcount: Define constants for saturation and max refcount values futex: Prevent exit livelock futex: Provide distinct return value when owner is exiting futex: Add mutex around futex exit futex: Provide state handling for exec() as well futex: Sanitize exit state handling futex: Mark the begin of futex exit explicitly futex: Set task::futex_state to DEAD right after handling futex exit futex: Split futex_mm_release() for exit/exec exit/exec: Seperate mm_release() futex: Replace PF_EXITPIDONE with a state ...
| * | futex: Mark the begin of futex exit explicitlyThomas Gleixner2019-11-201-12/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Instead of relying on PF_EXITING use an explicit state for the futex exit and set it in the futex exit function. This moves the smp barrier and the lock/unlock serialization into the futex code. As with the DEAD state this is restricted to the exit path as exec continues to use the same task struct. This allows to simplify that logic in a next step. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191106224556.539409004@linutronix.de
| * | futex: Set task::futex_state to DEAD right after handling futex exitThomas Gleixner2019-11-201-1/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Setting task::futex_state in do_exit() is rather arbitrarily placed for no reason. Move it into the futex code. Note, this is only done for the exit cleanup as the exec cleanup cannot set the state to FUTEX_STATE_DEAD because the task struct is still in active use. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191106224556.439511191@linutronix.de
| * | exit/exec: Seperate mm_release()Thomas Gleixner2019-11-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | mm_release() contains the futex exit handling. mm_release() is called from do_exit()->exit_mm() and from exec()->exec_mm(). In the exit_mm() case PF_EXITING and the futex state is updated. In the exec_mm() case these states are not touched. As the futex exit code needs further protections against exit races, this needs to be split into two functions. Preparatory only, no functional change. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191106224556.240518241@linutronix.de
| * | futex: Replace PF_EXITPIDONE with a stateThomas Gleixner2019-11-201-16/+2
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The futex exit handling relies on PF_ flags. That's suboptimal as it requires a smp_mb() and an ugly lock/unlock of the exiting tasks pi_lock in the middle of do_exit() to enforce the observability of PF_EXITING in the futex code. Add a futex_state member to task_struct and convert the PF_EXITPIDONE logic over to the new state. The PF_EXITING dependency will be cleaned up in a later step. This prepares for handling various futex exit issues later. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Ingo Molnar <mingo@kernel.org> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20191106224556.149449274@linutronix.de
* / exit: use pid_has_task() in do_wait()Christian Brauner2019-10-171-1/+1
|/ | | | | | | | | Replace hlist_empty() with the new pid_has_task() helper which is more idiomatic, easier to grep for, and unifies how callers perform this check. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Link: https://lore.kernel.org/r/20191017101832.5985-4-christian.brauner@ubuntu.com
* tasks, sched/core: With a grace period after finish_task_switch(), remove ↵Eric W. Biederman2019-09-251-67/+0
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | unnecessary code Remove work arounds that were written before there was a grace period after tasks left the runqueue in finish_task_switch(). In particular now that there tasks exiting the runqueue exprience a RCU grace period none of the work performed by task_rcu_dereference() excpet the rcu_dereference() is necessary so replace task_rcu_dereference() with rcu_dereference(). Remove the code in rcuwait_wait_event() that checks to ensure the current task has not exited. It is no longer necessary as it is guaranteed that any running task will experience a RCU grace period after it leaves the run queueue. Remove the comment in rcuwait_wake_up() as it is no longer relevant. Ref: 8f95c90ceb54 ("sched/wait, RCU: Introduce rcuwait machinery") Ref: 150593bf8693 ("sched/api: Introduce task_rcu_dereference() and try_get_task_struct()") Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/87lfurdpk9.fsf_-_@x220.int.ebiederm.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* tasks: Add a count of task RCU usersEric W. Biederman2019-09-251-1/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | Add a count of the number of RCU users (currently 1) of the task struct so that we can later add the scheduler case and get rid of the very subtle task_rcu_dereference(), and just use rcu_dereference(). As suggested by Oleg have the count overlap rcu_head so that no additional space in task_struct is required. Inspired-by: Linus Torvalds <torvalds@linux-foundation.org> Inspired-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Chris Metcalf <cmetcalf@ezchip.com> Cc: Christoph Lameter <cl@linux.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Kirill Tkhai <tkhai@yandex.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Paul E. McKenney <paulmck@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Russell King - ARM Linux admin <linux@armlinux.org.uk> Cc: Thomas Gleixner <tglx@linutronix.de> Link: https://lkml.kernel.org/r/87woebdplt.fsf_-_@x220.int.ebiederm.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge tag 'core-process-v5.4' of ↵Linus Torvalds2019-09-161-4/+34
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux Pull pidfd/waitid updates from Christian Brauner: "This contains two features and various tests. First, it adds support for waiting on process through pidfds by adding the P_PIDFD type to the waitid() syscall. This completes the basic functionality of the pidfd api (cf. [1]). In the meantime we also have a new adition to the userspace projects that make use of the pidfd api. The qt project was nice enough to send a mail pointing out that they have a pr up to switch to the pidfd api (cf. [2]). Second, this tag contains an extension to the waitid() syscall to make it possible to wait on the current process group in a race free manner (even though the actual problem is very unlikely) by specifing 0 together with the P_PGID type. This extension traces back to a discussion on the glibc development mailing list. There are also a range of tests for the features above. Additionally, the test-suite which detected the pidfd-polling race we fixed in [3] is included in this tag" [1] https://lwn.net/Articles/794707/ [2] https://codereview.qt-project.org/c/qt/qtbase/+/108456 [3] commit b191d6491be6 ("pidfd: fix a poll race when setting exit_state") * tag 'core-process-v5.4' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: waitid: Add support for waiting for the current process group tests: add pidfd poll tests tests: move common definitions and functions into pidfd.h pidfd: add pidfd_wait tests pidfd: add P_PIDFD to waitid()
| * waitid: Add support for waiting for the current process groupEric W. Biederman2019-09-101-2/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It was recently discovered that the linux version of waitid is not a superset of the other wait functions because it does not include support for waiting for the current process group. This has two downsides: 1. An extra system call is needed to get the current process group. 2. After the current process group is received and before it is passed to waitid a signal could arrive causing the current process group to change. Inherent race-conditions as these make it impossible for userspace to emulate this functionaly and thus violate async-signal safety requirements for waitpid. Arguments can be made for using a different choice of idtype and id for this case but the BSDs already use this P_PGID and 0 to indicate waiting for the current process's process group. So be nice to user space programmers and don't introduce an unnecessary incompatibility. Some people have noted that the posix description is that waitpid will wait for the current process group, and that in the presence of pthreads that process group can change. To get clarity on this issue I looked at XNU, FreeBSD, and Luminos. All of those flavors of unix waited for the current process group at the time of call and as written could not adapt to the process group changing after the call. At one point Linux did adapt to the current process group changing but that stopped in 161550d74c07 ("pid: sys_wait... fixes"). It has been over 11 years since Linux has that behavior, no programs that fail with the change in behavior have been reported, and I could not find any other unix that does this. So I think it is safe to clarify the definition of current process group, to current process group at the time of the wait function. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Palmer Dabbelt <palmer@sifive.com> Cc: Rich Felker <dalias@libc.org> Cc: Alistair Francis <alistair23@gmail.com> Cc: Zong Li <zongbox@gmail.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Florian Weimer <fweimer@redhat.com> Cc: Adhemerval Zanella <adhemerval.zanella@linaro.org> Cc: GNU C Library <libc-alpha@sourceware.org> Link: https://lore.kernel.org/r/20190814154400.6371-2-christian.brauner@ubuntu.com
| * pidfd: add P_PIDFD to waitid()Christian Brauner2019-08-011-3/+30
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This adds the P_PIDFD type to waitid(). One of the last remaining bits for the pidfd api is to make it possible to wait on pidfds. With P_PIDFD added to waitid() the parts of userspace that want to use the pidfd api to exclusively manage processes can do so now. One of the things this will unblock in the future is the ability to make it possible to retrieve the exit status via waitid(P_PIDFD) for non-parent processes if handed a _suitable_ pidfd that has this feature set. This is similar to what you can do on FreeBSD with kqueue(). It might even end up being possible to wait on a process as a non-parent if an appropriate property is enabled on the pidfd. With P_PIDFD no scoping of the process identified by the pidfd is possible, i.e. it explicitly blocks things such as wait4(-1), wait4(0), waitid(P_ALL), waitid(P_PGID) etc. It only allows for semantics equivalent to wait4(pid), waitid(P_PID). Users that need scoping should rely on pid-based wait*() syscalls for now. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Oleg Nesterov <oleg@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: David Howells <dhowells@redhat.com> Cc: Jann Horn <jannh@google.com> Cc: Andy Lutomirsky <luto@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Aleksa Sarai <cyphar@cyphar.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Link: https://lore.kernel.org/r/20190727222229.6516-2-christian@brauner.io
* | exit: make setting exit_state consistentChristian Brauner2019-07-301-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Since commit b191d6491be6 ("pidfd: fix a poll race when setting exit_state") we unconditionally set exit_state to EXIT_ZOMBIE before calling into do_notify_parent(). This was done to eliminate a race when querying exit_state in do_notify_pidfd(). Back then we decided to do the absolute minimal thing to fix this and not touch the rest of the exit_notify() function where exit_state is set. Since this fix has not caused any issues change the setting of exit_state to EXIT_DEAD in the autoreap case to account for the fact hat exit_state is set to EXIT_ZOMBIE unconditionally. This fix was planned but also explicitly requested in [1] and makes the whole code more consistent. /* References */ [1]: https://lore.kernel.org/lkml/CAHk-=wigcxGFR2szue4wavJtH5cYTTeNES=toUBVGsmX0rzX+g@mail.gmail.com Signed-off-by: Christian Brauner <christian@brauner.io> Acked-by: Oleg Nesterov <oleg@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org>
* | pidfd: fix a poll race when setting exit_stateSuren Baghdasaryan2019-07-221-0/+1
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a race between reading task->exit_state in pidfd_poll and writing it after do_notify_parent calls do_notify_pidfd. Expected sequence of events is: CPU 0 CPU 1 ------------------------------------------------ exit_notify do_notify_parent do_notify_pidfd tsk->exit_state = EXIT_DEAD pidfd_poll if (tsk->exit_state) However nothing prevents the following sequence: CPU 0 CPU 1 ------------------------------------------------ exit_notify do_notify_parent do_notify_pidfd pidfd_poll if (tsk->exit_state) tsk->exit_state = EXIT_DEAD This causes a polling task to wait forever, since poll blocks because exit_state is 0 and the waiting task is not notified again. A stress test continuously doing pidfd poll and process exits uncovered this bug. To fix it, we make sure that the task's exit_state is always set before calling do_notify_pidfd. Fixes: b53b0b9d9a6 ("pidfd: add polling support") Cc: kernel-team@android.com Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Link: https://lore.kernel.org/r/20190717172100.261204-1-joel@joelfernandes.org [christian@brauner.io: adapt commit message and drop unneeded changes from wait_task_zombie] Signed-off-by: Christian Brauner <christian@brauner.io>
* cgroup: Call cgroup_release() before __exit_signal()Tejun Heo2019-05-311-1/+1
| | | | | | | | | | | | cgroup_release() calls cgroup_subsys->release() which is used by the pids controller to uncharge its pid. We want to use it to manage iteration of dying tasks which requires putting it before __unhash_process(). Move cgroup_release() above __exit_signal(). While this makes it uncharge before the pid is freed, pid is RCU freed anyway and the window is very narrow. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Oleg Nesterov <oleg@redhat.com>
* treewide: Add SPDX license identifier for missed filesThomas Gleixner2019-05-211-0/+1
| | | | | | | | | | | | | | | | | Add SPDX license identifiers to all files which: - Have no license information of any form - Have EXPORT_.*_SYMBOL_GPL inside which was used in the initial scan/conversion to ignore the file These files fall under the project license, GPL v2 only. The resulting SPDX license identifier is: GPL-2.0-only Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* mm: change mm_update_next_owner() to update mm->owner with WRITE_ONCEAndrea Arcangeli2019-05-141-3/+3
| | | | | | | | | | | | | | | | | | | | | | The RCU reader uses rcu_dereference() inside rcu_read_lock critical sections, so the writer shall use WRITE_ONCE. Just a cleanup, we still rely on gcc to emit atomic writes in other places. Link: http://lkml.kernel.org/r/20190325225636.11635-3-aarcange@redhat.com Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Jann Horn <jannh@google.com> Cc: Jason Gunthorpe <jgg@mellanox.com> Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Xu <peterx@redhat.com> Cc: zhong jiang <zhongjiang@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-5.1' of ↵Linus Torvalds2019-03-071-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: - Oleg's pids controller accounting update which gets rid of rcu delay in pids accounting updates - rstat (cgroup hierarchical stat collection mechanism) optimization - Doc updates * 'for-5.1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cpuset: remove unused task_has_mempolicy() cgroup, rstat: Don't flush subtree root unless necessary cgroup: add documentation for pids.events file Documentation: cgroup-v2: eliminate markup warnings MAINTAINERS: Update cgroup entry cgroup/pids: turn cgroup_subsys->free() into cgroup_subsys->release() to fix the accounting
| * cgroup/pids: turn cgroup_subsys->free() into cgroup_subsys->release() to fix ↵Oleg Nesterov2019-01-311-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | the accounting The only user of cgroup_subsys->free() callback is pids_cgrp_subsys which needs pids_free() to uncharge the pid. However, ->free() is called from __put_task_struct()->cgroup_free() and this is too late. Even the trivial program which does for (;;) { int pid = fork(); assert(pid >= 0); if (pid) wait(NULL); else exit(0); } can run out of limits because release_task()->call_rcu(delayed_put_task_struct) implies an RCU gp after the task/pid goes away and before the final put(). Test-case: mkdir -p /tmp/CG mount -t cgroup2 none /tmp/CG echo '+pids' > /tmp/CG/cgroup.subtree_control mkdir /tmp/CG/PID echo 2 > /tmp/CG/PID/pids.max perl -e 'while ($p = fork) { wait; } $p // die "fork failed: $!\n"' & echo $! > /tmp/CG/PID/cgroup.procs Without this patch the forking process fails soon after migration. Rename cgroup_subsys->free() to cgroup_subsys->release() and move the callsite into the new helper, cgroup_release(), called by release_task() which actually frees the pid(s). Reported-by: Herton R. Krzesinski <hkrzesin@redhat.com> Reported-by: Jan Stancek <jstancek@redhat.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org>
* | kernel/exit.c: release ptraced tasks before zap_pid_ns_processesAndrei Vagin2019-02-011-2/+10
|/ | | | | | | | | | | | | | | | | | | | | Currently, exit_ptrace() adds all ptraced tasks in a dead list, then zap_pid_ns_processes() waits on all tasks in a current pidns, and only then are tasks from the dead list released. zap_pid_ns_processes() can get stuck on waiting tasks from the dead list. In this case, we will have one unkillable process with one or more dead children. Thanks to Oleg for the advice to release tasks in find_child_reaper(). Link: http://lkml.kernel.org/r/20190110175200.12442-1-avagin@gmail.com Fixes: 7c8bd2322c7f ("exit: ptrace: shift "reap dead" code from exit_ptrace() to forget_original_parent()") Signed-off-by: Andrei Vagin <avagin@gmail.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sched/wait: Fix rcuwait_wake_up() orderingPrateek Sood2019-01-211-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | For some peculiar reason rcuwait_wake_up() has the right barrier in the comment, but not in the code. This mistake has been observed to cause a deadlock in the following situation: P1 P2 percpu_up_read() percpu_down_write() rcu_sync_is_idle() // false rcu_sync_enter() ... __percpu_up_read() [S] ,- __this_cpu_dec(*sem->read_count) | smp_rmb(); [L] | task = rcu_dereference(w->task) // NULL | | [S] w->task = current | smp_mb(); | [L] readers_active_check() // fail `-> <store happens here> Where the smp_rmb() (obviously) fails to constrain the store. [ peterz: Added changelog. ] Signed-off-by: Prateek Sood <prsood@codeaurora.org> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reviewed-by: Andrea Parri <andrea.parri@amarulasolutions.com> Acked-by: Davidlohr Bueso <dbueso@suse.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Fixes: 8f95c90ceb54 ("sched/wait, RCU: Introduce rcuwait machinery") Link: https://lkml.kernel.org/r/1543590656-7157-1-git-send-email-prsood@codeaurora.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds2019-01-161-0/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull networking fixes from David Miller: 1) Fix regression in multi-SKB responses to RTM_GETADDR, from Arthur Gautier. 2) Fix ipv6 frag parsing in openvswitch, from Yi-Hung Wei. 3) Unbounded recursion in ipv4 and ipv6 GUE tunnels, from Stefano Brivio. 4) Use after free in hns driver, from Yonglong Liu. 5) icmp6_send() needs to handle the case of NULL skb, from Eric Dumazet. 6) Missing rcu read lock in __inet6_bind() when operating on mapped addresses, from David Ahern. 7) Memory leak in tipc-nl_compat_publ_dump(), from Gustavo A. R. Silva. 8) Fix PHY vs r8169 module loading ordering issues, from Heiner Kallweit. 9) Fix bridge vlan memory leak, from Ido Schimmel. 10) Dev refcount leak in AF_PACKET, from Jason Gunthorpe. 11) Infoleak in ipv6_local_error(), flow label isn't completely initialized. From Eric Dumazet. 12) Handle mv88e6390 errata, from Andrew Lunn. 13) Making vhost/vsock CID hashing consistent, from Zha Bin. 14) Fix lack of UMH cleanup when it unexpectedly exits, from Taehee Yoo. 15) Bridge forwarding must clear skb->tstamp, from Paolo Abeni. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (87 commits) bnxt_en: Fix context memory allocation. bnxt_en: Fix ring checking logic on 57500 chips. mISDN: hfcsusb: Use struct_size() in kzalloc() net: clear skb->tstamp in bridge forwarding path net: bpfilter: disallow to remove bpfilter module while being used net: bpfilter: restart bpfilter_umh when error occurred net: bpfilter: use cleanup callback to release umh_info umh: add exit routine for UMH process isdn: i4l: isdn_tty: Fix some concurrency double-free bugs vhost/vsock: fix vhost vsock cid hashing inconsistent net: stmmac: Prevent RX starvation in stmmac_napi_poll() net: stmmac: Fix the logic of checking if RX Watchdog must be enabled net: stmmac: Check if CBS is supported before configuring net: stmmac: dwxgmac2: Only clear interrupts that are active net: stmmac: Fix PCI module removal leak tools/bpf: fix bpftool map dump with bitfields tools/bpf: test btf bitfield with >=256 struct member offset bpf: fix bpffs bitfield pretty print net: ethernet: mediatek: fix warning in phy_start_aneg tcp: change txhash on SYN-data timeout ...
| * umh: add exit routine for UMH processTaehee Yoo2019-01-111-0/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | A UMH process which is created by the fork_usermode_blob() such as bpfilter needs to release members of the umh_info when process is terminated. But the do_exit() does not release members of the umh_info. hence module which uses UMH needs own code to detect whether UMH process is terminated or not. But this implementation needs extra code for checking the status of UMH process. it eventually makes the code more complex. The new PF_UMH flag is added and it is used to identify UMH processes. The exit_umh() does not release members of the umh_info. Hence umh_info->cleanup callback should release both members of the umh_info and the private data. Suggested-by: David S. Miller <davem@davemloft.net> Signed-off-by: Taehee Yoo <ap420073@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
* | make 'user_access_begin()' do 'access_ok()'Linus Torvalds2019-01-041-4/+2
|/ | | | | | | | | | | | | | | | | | | | | | | Originally, the rule used to be that you'd have to do access_ok() separately, and then user_access_begin() before actually doing the direct (optimized) user access. But experience has shown that people then decide not to do access_ok() at all, and instead rely on it being implied by other operations or similar. Which makes it very hard to verify that the access has actually been range-checked. If you use the unsafe direct user accesses, hardware features (either SMAP - Supervisor Mode Access Protection - on x86, or PAN - Privileged Access Never - on ARM) do force you to use user_access_begin(). But nothing really forces the range check. By putting the range check into user_access_begin(), we actually force people to do the right thing (tm), and the range check vill be visible near the actual accesses. We have way too long a history of people trying to avoid them. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Remove 'type' argument from access_ok() functionLinus Torvalds2019-01-031-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Nobody has actually used the type (VERIFY_READ vs VERIFY_WRITE) argument of the user address range verification function since we got rid of the old racy i386-only code to walk page tables by hand. It existed because the original 80386 would not honor the write protect bit when in kernel mode, so you had to do COW by hand before doing any user access. But we haven't supported that in a long time, and these days the 'type' argument is a purely historical artifact. A discussion about extending 'user_access_begin()' to do the range checking resulted this patch, because there is no way we're going to move the old VERIFY_xyz interface to that model. And it's best done at the end of the merge window when I've done most of my merges, so let's just get this done once and for all. This patch was mostly done with a sed-script, with manual fix-ups for the cases that weren't of the trivial 'access_ok(VERIFY_xyz' form. There were a couple of notable cases: - csky still had the old "verify_area()" name as an alias. - the iter_iov code had magical hardcoded knowledge of the actual values of VERIFY_{READ,WRITE} (not that they mattered, since nothing really used it) - microblaze used the type argument for a debug printout but other than those oddities this should be a total no-op patch. I tried to fix up all architectures, did fairly extensive grepping for access_ok() uses, and the changes are trivial, but I may have missed something. Any missed conversion should be trivially fixable, though. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* signal: Pass pid type into group_send_sig_infoEric W. Biederman2018-07-211-1/+2
| | | | | | | | This passes the information we already have at the call sight into group_send_sig_info. Ultimatelly allowing for to better handle signals sent to a group of processes. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* pid: Implement PIDTYPE_TGIDEric W. Biederman2018-07-211-0/+1
| | | | | | | | | | | | | | | | | | | | | | Everywhere except in the pid array we distinguish between a tasks pid and a tasks tgid (thread group id). Even in the enumeration we want that distinction sometimes so we have added __PIDTYPE_TGID. With leader_pid we almost have an implementation of PIDTYPE_TGID in struct signal_struct. Add PIDTYPE_TGID as a first class member of the pid_type enumeration and into the pids array. Then remove the __PIDTYPE_TGID special case and the leader_pid in signal_struct. The net size increase is just an extra pointer added to struct pid and an extra pair of pointers of an hlist_node added to task_struct. The effect on code maintenance is the removal of a number of special cases today and the potential to remove many more special cases as PIDTYPE_TGID gets used to it's fullest. The long term potential is allowing zombie thread group leaders to exit, which will remove a lot more special cases in the code. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* pids: Move task_pid_type into sched/signal.hEric W. Biederman2018-07-211-8/+0
| | | | | | | The function is general and inline so there is no need to hide it inside of exit.c Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* kernel: use kernel_wait4() instead of sys_wait4()Dominik Brodowski2018-04-021-1/+1
| | | | | | | | | | | | | | | All call sites of sys_wait4() set *rusage to NULL. Therefore, there is no need for the copy_to_user() handling of *rusage, and we can use kernel_wait4() directly. This patch is part of a series which removes in-kernel calls to syscalls. On this basis, the syscall entry path can be streamlined. For details, see http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net Acked-by: Luis R. Rodriguez <mcgrof@kernel.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
* kernel/exit.c: export abort() to modulesAndrew Morton2018-01-041-0/+1
| | | | | | | | | | | | | | | | | gcc -fisolate-erroneous-paths-dereference can generate calls to abort() from modular code too. [arnd@arndb.de: drop duplicate exports of abort()] Link: http://lkml.kernel.org/r/20180102103311.706364-1-arnd@arndb.de Reported-by: Vineet Gupta <Vineet.Gupta1@synopsys.com> Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Alexey Brodkin <Alexey.Brodkin@synopsys.com> Cc: Russell King <rmk+kernel@armlinux.org.uk> Cc: Jose Abreu <Jose.Abreu@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* arch: define weak abort()Sudip Mukherjee2017-12-141-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | gcc toggle -fisolate-erroneous-paths-dereference (default at -O2 onwards) isolates faulty code paths such as null pointer access, divide by zero etc. If gcc port doesnt implement __builtin_trap, an abort() is generated which causes kernel link error. In this case, gcc is generating abort due to 'divide by zero' in lib/mpi/mpih-div.c. Currently 'frv' and 'arc' are failing. Previously other arch was also broken like m32r was fixed by commit d22e3d69ee1a ("m32r: fix build failure"). Let's define this weak function which is common for all arch and fix the problem permanently. We can even remove the arch specific 'abort' after this is done. Link: http://lkml.kernel.org/r/1513118956-8718-1-git-send-email-sudipm.mukherjee@gmail.com Signed-off-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Cc: Alexey Brodkin <Alexey.Brodkin@synopsys.com> Cc: Vineet Gupta <Vineet.Gupta1@synopsys.com> Cc: Sudip Mukherjee <sudipm.mukherjee@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* locking/atomics: COCCINELLE/treewide: Convert trivial ACCESS_ONCE() patterns ↵Mark Rutland2017-10-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | to READ_ONCE()/WRITE_ONCE() Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
* waitid(): Avoid unbalanced user_access_end() on access_ok() errorKees Cook2017-10-201-2/+2
| | | | | | | | | | | | As pointed out by Linus and David, the earlier waitid() fix resulted in a (currently harmless) unbalanced user_access_end() call. This fixes it to just directly return EFAULT on access_ok() failure. Fixes: 96ca579a1ecc ("waitid(): Add missing access_ok() checks") Acked-by: David Daney <david.daney@cavium.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* waitid(): Add missing access_ok() checksKees Cook2017-10-091-0/+6
| | | | | | | | | | | | | Adds missing access_ok() checks. CVE-2017-5123 Reported-by: Chris Salls <chrissalls5@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Al Viro <viro@zeniv.linux.org.uk> Fixes: 4c48abe91be0 ("waitid(): switch copyout of siginfo to unsafe_put_user()") Cc: stable@kernel.org # 4.13 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix infoleak in waitid(2)Al Viro2017-09-291-13/+10
| | | | | | | | | | | | kernel_waitid() can return a PID, an error or 0. rusage is filled in the first case and waitid(2) rusage should've been copied out exactly in that case, *not* whenever kernel_waitid() has not returned an error. Compat variant shares that braino; none of kernel_wait4() callers do, so the below ought to fix it. Reported-and-tested-by: Alexander Potapenko <glider@google.com> Fixes: ce72a16fa705 ("wait4(2)/waitid(2): separate copying rusage to userland") Cc: stable@vger.kernel.org # v4.13 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* Merge branch 'for-linus' of ↵Linus Torvalds2017-09-111-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace Pull namespace updates from Eric Biederman: "Life has been busy and I have not gotten half as much done this round as I would have liked. I delayed it so that a minor conflict resolution with the mips tree could spend a little time in linux-next before I sent this pull request. This includes two long delayed user namespace changes from Kirill Tkhai. It also includes a very useful change from Serge Hallyn that allows the security capability attribute to be used inside of user namespaces. The practical effect of this is people can now untar tarballs and install rpms in user namespaces. It had been suggested to generalize this and encode some of the namespace information information in the xattr name. Upon close inspection that makes the things that should be hard easy and the things that should be easy more expensive. Then there is my bugfix/cleanup for signal injection that removes the magic encoding of the siginfo union member from the kernel internal si_code. The mips folks reported the case where I had used FPE_FIXME me is impossible so I have remove FPE_FIXME from mips, while at the same time including a return statement in that case to keep gcc from complaining about unitialized variables. I almost finished the work to get make copy_siginfo_to_user a trivial copy to user. The code is available at: git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace.git neuter-copy_siginfo_to_user-v3 But I did not have time/energy to get the code posted and reviewed before the merge window opened. I was able to see that the security excuse for just copying fields that we know are initialized doesn't work in practice there are buggy initializations that don't initialize the proper fields in siginfo. So we still sometimes copy unitialized data to userspace" * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: Introduce v3 namespaced file capabilities mips/signal: In force_fcr31_sig return in the impossible case signal: Remove kernel interal si_code magic fcntl: Don't use ambiguous SIG_POLL si_codes prctl: Allow local CAP_SYS_ADMIN changing exe_file security: Use user_namespace::level to avoid redundant iterations in cap_capable() userns,pidns: Verify the userns for new pid namespaces signal/testing: Don't look for __SI_FAULT in userspace signal/mips: Document a conflict with SI_USER with SIGFPE signal/sparc: Document a conflict with SI_USER with SIGFPE signal/ia64: Document a conflict with SI_USER with SIGFPE signal/alpha: Document a conflict with SI_USER for SIGTRAP
| * signal: Remove kernel interal si_code magicEric W. Biederman2017-07-241-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | struct siginfo is a union and the kernel since 2.4 has been hiding a union tag in the high 16bits of si_code using the values: __SI_KILL __SI_TIMER __SI_POLL __SI_FAULT __SI_CHLD __SI_RT __SI_MESGQ __SI_SYS While this looks plausible on the surface, in practice this situation has not worked well. - Injected positive signals are not copied to user space properly unless they have these magic high bits set. - Injected positive signals are not reported properly by signalfd unless they have these magic high bits set. - These kernel internal values leaked to userspace via ptrace_peek_siginfo - It was possible to inject these kernel internal values and cause the the kernel to misbehave. - Kernel developers got confused and expected these kernel internal values in userspace in kernel self tests. - Kernel developers got confused and set si_code to __SI_FAULT which is SI_USER in userspace which causes userspace to think an ordinary user sent the signal and that it was not kernel generated. - The values make it impossible to reorganize the code to transform siginfo_copy_to_user into a plain copy_to_user. As si_code must be massaged before being passed to userspace. So remove these kernel internal si codes and make the kernel code simpler and more maintainable. To replace these kernel internal magic si_codes introduce the helper function siginfo_layout, that takes a signal number and an si_code and computes which union member of siginfo is being used. Have siginfo_layout return an enumeration so that gcc will have enough information to warn if a switch statement does not handle all of union members. A couple of architectures have a messed up ABI that defines signal specific duplications of SI_USER which causes more special cases in siginfo_layout than I would like. The good news is only problem architectures pay the cost. Update all of the code that used the previous magic __SI_ values to use the new SIL_ values and to call siginfo_layout to get those values. Escept where not all of the cases are handled remove the defaults in the switch statements so that if a new case is missed in the future the lack will show up at compile time. Modify the code that copies siginfo si_code to userspace to just copy the value and not cast si_code to a short first. The high bits are no longer used to hold a magic union member. Fixup the siginfo header files to stop including the __SI_ values in their constants and for the headers that were missing it to properly update the number of si_codes for each signal type. The fixes to copy_siginfo_from_user32 implementations has the interesting property that several of them perviously should never have worked as the __SI_ values they depended up where kernel internal. With that dependency gone those implementations should work much better. The idea of not passing the __SI_ values out to userspace and then not reinserting them has been tested with criu and criu worked without changes. Ref: 2.4.0-test1 Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
* | Merge branch 'locking-core-for-linus' of ↵Linus Torvalds2017-09-041-0/+1
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull locking updates from Ingo Molnar: - Add 'cross-release' support to lockdep, which allows APIs like completions, where it's not the 'owner' who releases the lock, to be tracked. It's all activated automatically under CONFIG_PROVE_LOCKING=y. - Clean up (restructure) the x86 atomics op implementation to be more readable, in preparation of KASAN annotations. (Dmitry Vyukov) - Fix static keys (Paolo Bonzini) - Add killable versions of down_read() et al (Kirill Tkhai) - Rework and fix jump_label locking (Marc Zyngier, Paolo Bonzini) - Rework (and fix) tlb_flush_pending() barriers (Peter Zijlstra) - Remove smp_mb__before_spinlock() and convert its usages, introduce smp_mb__after_spinlock() (Peter Zijlstra) * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (56 commits) locking/lockdep/selftests: Fix mixed read-write ABBA tests sched/completion: Avoid unnecessary stack allocation for COMPLETION_INITIALIZER_ONSTACK() acpi/nfit: Fix COMPLETION_INITIALIZER_ONSTACK() abuse locking/pvqspinlock: Relax cmpxchg's to improve performance on some architectures smp: Avoid using two cache lines for struct call_single_data locking/lockdep: Untangle xhlock history save/restore from task independence locking/refcounts, x86/asm: Disable CONFIG_ARCH_HAS_REFCOUNT for the time being futex: Remove duplicated code and fix undefined behaviour Documentation/locking/atomic: Finish the document... locking/lockdep: Fix workqueue crossrelease annotation workqueue/lockdep: 'Fix' flush_work() annotation locking/lockdep/selftests: Add mixed read-write ABBA tests mm, locking/barriers: Clarify tlb_flush_pending() barriers locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE and CONFIG_LOCKDEP_COMPLETIONS truly non-interactive locking/lockdep: Explicitly initialize wq_barrier::done::map locking/lockdep: Rename CONFIG_LOCKDEP_COMPLETE to CONFIG_LOCKDEP_COMPLETIONS locking/lockdep: Reword title of LOCKDEP_CROSSRELEASE config locking/lockdep: Make CONFIG_LOCKDEP_CROSSRELEASE part of CONFIG_PROVE_LOCKING locking/refcounts, x86/asm: Implement fast refcount overflow protection locking/lockdep: Fix the rollback and overwrite detection logic in crossrelease ...
| * | locking/lockdep: Implement the 'crossrelease' featureByungchul Park2017-08-101-0/+1
| |/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Lockdep is a runtime locking correctness validator that detects and reports a deadlock or its possibility by checking dependencies between locks. It's useful since it does not report just an actual deadlock but also the possibility of a deadlock that has not actually happened yet. That enables problems to be fixed before they affect real systems. However, this facility is only applicable to typical locks, such as spinlocks and mutexes, which are normally released within the context in which they were acquired. However, synchronization primitives like page locks or completions, which are allowed to be released in any context, also create dependencies and can cause a deadlock. So lockdep should track these locks to do a better job. The 'crossrelease' implementation makes these primitives also be tracked. Signed-off-by: Byungchul Park <byungchul.park@lge.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: akpm@linux-foundation.org Cc: boqun.feng@gmail.com Cc: kernel-team@lge.com Cc: kirill@shutemov.name Cc: npiggin@gmail.com Cc: walken@google.com Cc: willy@infradead.org Link: http://lkml.kernel.org/r/1502089981-21272-6-git-send-email-byungchul.park@lge.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
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*-. \ Merge branches 'doc.2017.08.17a', 'fixes.2017.08.17a', ↵Paul E. McKenney2017-08-171-6/+4
|\ \ \ | |_|/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'hotplug.2017.07.25b', 'misc.2017.08.17a', 'spin_unlock_wait_no.2017.08.17a', 'srcu.2017.07.27c' and 'torture.2017.07.24c' into HEAD doc.2017.08.17a: Documentation updates. fixes.2017.08.17a: RCU fixes. hotplug.2017.07.25b: CPU-hotplug updates. misc.2017.08.17a: Miscellaneous fixes outside of RCU (give or take conflicts). spin_unlock_wait_no.2017.08.17a: Remove spin_unlock_wait(). srcu.2017.07.27c: SRCU updates. torture.2017.07.24c: Torture-test updates.
| | * exit: Replace spin_unlock_wait() with lock/unlock pairPaul E. McKenney2017-08-171-1/+2
| |/ |/| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is no agreed-upon definition of spin_unlock_wait()'s semantics, and it appears that all callers could do just as well with a lock/unlock pair. This commit therefore replaces the spin_unlock_wait() call in do_exit() with spin_lock() followed immediately by spin_unlock(). This should be safe from a performance perspective because the lock is a per-task lock, and this is happening only at task-exit time. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Andrea Parri <parri.andrea@gmail.com> Cc: Linus Torvalds <torvalds@linux-foundation.org>
| * rcu: Create reasonable API for do_exit() TASKS_RCU processingPaul E. McKenney2017-08-171-5/+2
|/ | | | | | | | | Currently, the exit-time support for TASKS_RCU is open-coded in do_exit(). This commit creates exit_tasks_rcu_start() and exit_tasks_rcu_finish() APIs for do_exit() use. This has the benefit of confining the use of the tasks_rcu_exit_srcu variable to one file, allowing it to become static. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* kernel/exit.c: avoid undefined behaviour when calling wait4()zhongjiang2017-07-101-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | wait4(-2147483648, 0x20, 0, 0xdd0000) triggers: UBSAN: Undefined behaviour in kernel/exit.c:1651:9 The related calltrace is as follows: negation of -2147483648 cannot be represented in type 'int': CPU: 9 PID: 16482 Comm: zj Tainted: G B ---- ------- 3.10.0-327.53.58.71.x86_64+ #66 Hardware name: Huawei Technologies Co., Ltd. Tecal RH2285 /BC11BTSA , BIOS CTSAV036 04/27/2011 Call Trace: dump_stack+0x19/0x1b ubsan_epilogue+0xd/0x50 __ubsan_handle_negate_overflow+0x109/0x14e SyS_wait4+0x1cb/0x1e0 system_call_fastpath+0x16/0x1b Exclude the overflow to avoid the UBSAN warning. Link: http://lkml.kernel.org/r/1497264618-20212-1-git-send-email-zhongjiang@huawei.com Signed-off-by: zhongjiang <zhongjiang@huawei.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Xishi Qiu <qiuxishi@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* fix waitid(2) breakageAl Viro2017-07-081-5/+12
| | | | | | | | | | We lose the distinction between "found a PID" and "nothing, but that's not an error" a bit too early in waitid(). Easily fixed, fortunately... Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de> Fixes: 67d7ddded322 ("waitid(2): leave copyout of siginfo to syscall itself") Tested-by: Markus Trippelsdorf <markus@trippelsdorf.de> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* kernel/exit.c: don't include unused userfaultfd_k.hMike Rapoport2017-07-061-1/+0
| | | | | | | | | | | | Commit dd0db88d8094 ("userfaultfd: non-cooperative: rollback userfaultfd_exit") removed userfaultfd callback from exit() which makes the include of <linux/userfaultfd_k.h> unnecessary. Link: http://lkml.kernel.org/r/1494930907-3060-1-git-send-email-rppt@linux.vnet.ibm.com Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'work.sys_wait' of ↵Linus Torvalds2017-07-051-143/+164
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs Pull wait syscall updates from Al Viro: "Consolidating sys_wait* and compat counterparts. Gets rid of set_fs()/double-copy mess, simplifies the whole thing (lifting the copyouts to the syscalls means less headache in the part that does actual work - fewer failure exits, to start with), gets rid of the overhead of field-by-field __put_user()" * 'work.sys_wait' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: osf_wait4: switch to kernel_wait4() waitid(): switch copyout of siginfo to unsafe_put_user() wait_task_zombie: consolidate info logics kill wait_noreap_copyout() lift getrusage() from wait_noreap_copyout() waitid(2): leave copyout of siginfo to syscall itself kernel_wait4()/kernel_waitid(): delay copying status to userland wait4(2)/waitid(2): separate copying rusage to userland move compat wait4 and waitid next to native variants
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-24 07:48:25 +0000