[moderation] [fs?] KCSAN: data-race in __ep_remove / __fput (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 047371968ffc Merge tag 'v6.8-p3' of git://git.kernel.org/p..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16e94924180000
kernel config: https://syzkaller.appspot.com/x/.config?x=3cd0dc1b46a5bc5c
dashboard link: https://syzkaller.appspot.com/bug?extid=2409b92bfc0d90a0f081
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [bra...@kernel.org ja...@suse.cz linux-...@vger.kernel.org linux-...@vger.kernel.org vi...@zeniv.linux.org.uk]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c52200287356/disk-04737196.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/820016a9b91b/vmlinux-04737196.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f66a09c33ecf/bzImage-04737196.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2409b9...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __ep_remove / __fput

write to 0xffff8881042fd4d0 of 8 bytes by task 21157 on cpu 1:
__ep_remove+0x3b8/0x440 fs/eventpoll.c:743
ep_remove_safe fs/eventpoll.c:781 [inline]
ep_clear_and_put+0x158/0x260 fs/eventpoll.c:817
ep_eventpoll_release+0x32/0x40 fs/eventpoll.c:833
__fput+0x299/0x630 fs/file_table.c:376
____fput+0x15/0x20 fs/file_table.c:404
task_work_run+0x135/0x1a0 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:108 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline]
syscall_exit_to_user_mode+0xbd/0x130 kernel/entry/common.c:212
do_syscall_64+0xda/0x1d0 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881042fd4d0 of 8 bytes by task 21156 on cpu 0:
eventpoll_release include/linux/eventpoll.h:45 [inline]
__fput+0x217/0x630 fs/file_table.c:367
__fput_sync+0x44/0x50 fs/file_table.c:461
__do_sys_close fs/open.c:1554 [inline]
__se_sys_close+0xfa/0x1a0 fs/open.c:1539
__x64_sys_close+0x1f/0x30 fs/open.c:1539
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0xffff8881037e36b0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21156 Comm: syz-executor.1 Not tainted 6.8.0-rc3-syzkaller-00047-g047371968ffc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================


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[syzbot]

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