KCSAN: data-race in complete_signal / do_group_exit (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8100a580 Merge tag 'x86-urgent-2020-12-06' of git://git.ke..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1077b203500000
kernel config: https://syzkaller.appspot.com/x/.config?x=4e0bdb085ef78711
dashboard link: https://syzkaller.appspot.com/bug?extid=80965c4789403a2c0b06
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project.git 913f6005669cfb590c99865a90bc51ed0983d09d)
CC: [ax...@kernel.dk chri...@brauner.io ebie...@xmission.com linux-...@vger.kernel.org liuzhi...@huawei.com ol...@redhat.com]

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+80965c...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in complete_signal / do_group_exit

write to 0xffff8881014f5af4 of 4 bytes by task 17819 on cpu 1:
complete_signal+0x4a7/0x5f0 kernel/signal.c:1045
__send_signal+0x666/0x780 kernel/signal.c:1181
send_signal+0x39f/0x3d0 kernel/signal.c:1242
do_send_sig_info+0x9b/0xe0 kernel/signal.c:1291
send_sig_info kernel/signal.c:1606 [inline]
send_sig+0x4f/0x60 kernel/signal.c:1616
pipe_write+0x7ec/0xd20 fs/pipe.c:470
call_write_iter include/linux/fs.h:1903 [inline]
new_sync_write fs/read_write.c:518 [inline]
vfs_write+0x6d4/0x7c0 fs/read_write.c:605
ksys_write+0xce/0x180 fs/read_write.c:658
__do_sys_write fs/read_write.c:670 [inline]
__se_sys_write fs/read_write.c:667 [inline]
__x64_sys_write+0x3e/0x50 fs/read_write.c:667
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8881014f5af4 of 4 bytes by task 17812 on cpu 0:
signal_group_exit include/linux/sched/signal.h:268 [inline]
do_group_exit+0x50/0x170 kernel/exit.c:889
__do_sys_exit_group+0xb/0x10 kernel/exit.c:917
__se_sys_exit_group+0x5/0x10 kernel/exit.c:915
__x64_sys_exit_group+0x16/0x20 kernel/exit.c:915
do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17812 Comm: syz-executor.3 Not tainted 5.10.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.