KCSAN: data-race in poll_schedule_timeout.constprop.0 / pollwake (3)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 5863cc79 x86, kcsan: Enable KCSAN for x86
git tree: https://github.com/google/ktsan.git kcsan
console output: https://syzkaller.appspot.com/x/log.txt?x=14356ecee00000
kernel config: https://syzkaller.appspot.com/x/.config?x=186a3142a4cdd1db
dashboard link: https://syzkaller.appspot.com/bug?extid=bd0076c6e839503096b5
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
CC: [linux-...@vger.kernel.org linux-...@vger.kernel.org
vi...@zeniv.linux.org.uk el...@google.com]

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

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+bd0076...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in poll_schedule_timeout.constprop.0 / pollwake

read to 0xffffc90000e53a20 of 4 bytes by task 19683 on cpu 0:
poll_schedule_timeout.constprop.0+0x50/0xc0 fs/select.c:242
do_select+0xd7f/0x1020 fs/select.c:603
core_sys_select+0x381/0x550 fs/select.c:677
do_pselect.constprop.0+0x11d/0x160 fs/select.c:759
__do_sys_pselect6 fs/select.c:784 [inline]
__se_sys_pselect6 fs/select.c:769 [inline]
__x64_sys_pselect6+0x12e/0x170 fs/select.c:769
do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffffc90000e53a20 of 4 bytes by task 19690 on cpu 1:
__pollwake fs/select.c:197 [inline]
pollwake+0xe3/0x140 fs/select.c:217
__wake_up_common+0x7b/0x180 kernel/sched/wait.c:93
__wake_up_common_lock+0x77/0xb0 kernel/sched/wait.c:123
__wake_up+0xe/0x10 kernel/sched/wait.c:142
wakeup_pipe_writers+0x74/0xb0 fs/splice.c:457
splice_from_pipe_next.part.0+0x17a/0x1d0 fs/splice.c:560
splice_from_pipe_next fs/splice.c:543 [inline]
__splice_from_pipe+0xa4/0x480 fs/splice.c:622
vmsplice_to_user fs/splice.c:1272 [inline]
do_vmsplice.part.0+0x1c5/0x210 fs/splice.c:1350
do_vmsplice fs/splice.c:1344 [inline]
__do_sys_vmsplice+0x15f/0x1c0 fs/splice.c:1371
__se_sys_vmsplice fs/splice.c:1353 [inline]
__x64_sys_vmsplice+0x5e/0x80 fs/splice.c:1353
do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19690 Comm: syz-executor.1 Not tainted 5.4.0-rc7+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
==================================================================


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[Marco Elver]

#syz upstream

> --
> You received this message because you are subscribed to the Google Groups "syzkaller-upstream-moderation" group.
> To unsubscribe from this group and stop receiving emails from it, send an email to syzkaller-upstream-m...@googlegroups.com.
> To view this discussion on the web visit https://groups.google.com/d/msgid/syzkaller-upstream-moderation/000000000000ff4d790598ed9799%40google.com.