linux-kernel - [syzbot] [fs?] KCSAN: data-race in __ep_remove / _

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Message-ID: <66edfb3c.050a0220.3195df.001a.GAE@google.com>
Date: Fri, 20 Sep 2024 15:46:20 -0700
From: syzbot <syzbot+3b6b32dc50537a49bb4a@...kaller.appspotmail.com>
To: brauner@...nel.org, jack@...e.cz, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org, syzkaller-bugs@...glegroups.com, 
	viro@...iv.linux.org.uk
Subject: [syzbot] [fs?] KCSAN: data-race in __ep_remove / __fput (5)

Hello,

syzbot found the following issue on:

HEAD commit:    baeb9a7d8b60 Merge tag 'sched-rt-2024-09-17' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=16080700580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=3b3c9c7ae5fde27e
dashboard link: https://syzkaller.appspot.com/bug?extid=3b6b32dc50537a49bb4a
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b0581f8f76ee/disk-baeb9a7d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/742809660d16/vmlinux-baeb9a7d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/628c7d467d97/bzImage-baeb9a7d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3b6b32dc50537a49bb4a@...kaller.appspotmail.com

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

write to 0xffff888117ce4690 of 8 bytes by task 3797 on cpu 1:
 __ep_remove+0x3c8/0x450 fs/eventpoll.c:826
 ep_remove_safe fs/eventpoll.c:864 [inline]
 ep_clear_and_put+0x158/0x260 fs/eventpoll.c:900
 ep_eventpoll_release+0x2c/0x40 fs/eventpoll.c:937
 __fput+0x17a/0x6d0 fs/file_table.c:431
 ____fput+0x1c/0x30 fs/file_table.c:459
 task_work_run+0x13a/0x1a0 kernel/task_work.c:228
 get_signal+0xf87/0x1100 kernel/signal.c:2690
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888117ce4690 of 8 bytes by task 3795 on cpu 0:
 eventpoll_release include/linux/eventpoll.h:45 [inline]
 __fput+0xee/0x6d0 fs/file_table.c:422
 ____fput+0x1c/0x30 fs/file_table.c:459
 task_work_run+0x13a/0x1a0 kernel/task_work.c:228
 get_signal+0xf87/0x1100 kernel/signal.c:2690
 arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x59/0x130 kernel/entry/common.c:218
 do_syscall_64+0xd6/0x1c0 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffff888103209140 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3795 Comm: syz.3.142 Not tainted 6.11.0-syzkaller-07341-gbaeb9a7d8b60 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
==================================================================


---
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