diff options
author | Kuniyuki Iwashima <kuniyu@amazon.com> | 2024-02-09 14:04:53 -0800 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2024-03-06 14:48:42 +0000 |
commit | 69e0f04460f4037e01e29f0d9675544f62aafca3 (patch) | |
tree | edb5409a6339e20145cc7efad48a2306aaa73a36 /net/unix | |
parent | be8a177250b2ba387a55ce37dd4a8046a0ccab55 (diff) | |
download | linux-stable-69e0f04460f4037e01e29f0d9675544f62aafca3.tar.gz linux-stable-69e0f04460f4037e01e29f0d9675544f62aafca3.tar.bz2 linux-stable-69e0f04460f4037e01e29f0d9675544f62aafca3.zip |
af_unix: Fix task hung while purging oob_skb in GC.
commit 25236c91b5ab4a26a56ba2e79b8060cf4e047839 upstream.
syzbot reported a task hung; at the same time, GC was looping infinitely
in list_for_each_entry_safe() for OOB skb. [0]
syzbot demonstrated that the list_for_each_entry_safe() was not actually
safe in this case.
A single skb could have references for multiple sockets. If we free such
a skb in the list_for_each_entry_safe(), the current and next sockets could
be unlinked in a single iteration.
unix_notinflight() uses list_del_init() to unlink the socket, so the
prefetched next socket forms a loop itself and list_for_each_entry_safe()
never stops.
Here, we must use while() and make sure we always fetch the first socket.
[0]:
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 PID: 5065 Comm: syz-executor236 Not tainted 6.8.0-rc3-syzkaller-00136-g1f719a2f3fa6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
RIP: 0010:preempt_count arch/x86/include/asm/preempt.h:26 [inline]
RIP: 0010:check_kcov_mode kernel/kcov.c:173 [inline]
RIP: 0010:__sanitizer_cov_trace_pc+0xd/0x60 kernel/kcov.c:207
Code: cc cc cc cc 66 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 65 48 8b 14 25 40 c2 03 00 <65> 8b 05 b4 7c 78 7e a9 00 01 ff 00 48 8b 34 24 74 0f f6 c4 01 74
RSP: 0018:ffffc900033efa58 EFLAGS: 00000283
RAX: ffff88807b077800 RBX: ffff88807b077800 RCX: 1ffffffff27b1189
RDX: ffff88802a5a3b80 RSI: ffffffff8968488d RDI: ffff88807b077f70
RBP: ffffc900033efbb0 R08: 0000000000000001 R09: fffffbfff27a900c
R10: ffffffff93d48067 R11: ffffffff8ae000eb R12: ffff88807b077800
R13: dffffc0000000000 R14: ffff88807b077e40 R15: 0000000000000001
FS: 0000000000000000(0000) GS:ffff8880b9500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000564f4fc1e3a8 CR3: 000000000d57a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
unix_gc+0x563/0x13b0 net/unix/garbage.c:319
unix_release_sock+0xa93/0xf80 net/unix/af_unix.c:683
unix_release+0x91/0xf0 net/unix/af_unix.c:1064
__sock_release+0xb0/0x270 net/socket.c:659
sock_close+0x1c/0x30 net/socket.c:1421
__fput+0x270/0xb80 fs/file_table.c:376
task_work_run+0x14f/0x250 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0xa8a/0x2ad0 kernel/exit.c:871
do_group_exit+0xd4/0x2a0 kernel/exit.c:1020
__do_sys_exit_group kernel/exit.c:1031 [inline]
__se_sys_exit_group kernel/exit.c:1029 [inline]
__x64_sys_exit_group+0x3e/0x50 kernel/exit.c:1029
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd5/0x270 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7f9d6cbdac09
Code: Unable to access opcode bytes at 0x7f9d6cbdabdf.
RSP: 002b:00007fff5952feb8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9d6cbdac09
RDX: 000000000000003c RSI: 00000000000000e7 RDI: 0000000000000000
RBP: 00007f9d6cc552b0 R08: ffffffffffffffb8 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 00007f9d6cc552b0
R13: 0000000000000000 R14: 00007f9d6cc55d00 R15: 00007f9d6cbabe70
</TASK>
Reported-by: syzbot+4fa4a2d1f5a5ee06f006@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=4fa4a2d1f5a5ee06f006
Fixes: 1279f9d9dec2 ("af_unix: Call kfree_skb() for dead unix_(sk)->oob_skb in GC.")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20240209220453.96053-1-kuniyu@amazon.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'net/unix')
-rw-r--r-- | net/unix/garbage.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/net/unix/garbage.c b/net/unix/garbage.c index 8f63f0b4bf01..2ff7ddbaa782 100644 --- a/net/unix/garbage.c +++ b/net/unix/garbage.c @@ -315,10 +315,11 @@ void unix_gc(void) __skb_queue_purge(&hitlist); #if IS_ENABLED(CONFIG_AF_UNIX_OOB) - list_for_each_entry_safe(u, next, &gc_candidates, link) { - struct sk_buff *skb = u->oob_skb; + while (!list_empty(&gc_candidates)) { + u = list_entry(gc_candidates.next, struct unix_sock, link); + if (u->oob_skb) { + struct sk_buff *skb = u->oob_skb; - if (skb) { u->oob_skb = NULL; kfree_skb(skb); } |