[moderation] [fs?] KCSAN: data-race in pipe_lock / pipe_release (17)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a75cb869a8cc Merge tag 'v7.0-rc1-ksmbd-server-fixes' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=121b755a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6b32b22d8934c136
dashboard link: https://syzkaller.appspot.com/bug?extid=ce000bbda60a56aa1370
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
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/751a264ebdc1/disk-a75cb869.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/5dc24b107dfb/vmlinux-a75cb869.xz
kernel image: https://storage.googleapis.com/syzbot-assets/343ca5c50f03/bzImage-a75cb869.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ce000b...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in pipe_lock / pipe_release

read-write to 0xffff88811df94bac of 4 bytes by task 6865 on cpu 0:
put_pipe_info fs/pipe.c:714 [inline]
pipe_release+0x16a/0x1d0 fs/pipe.c:744
__fput+0x29b/0x650 fs/file_table.c:469
____fput+0x1c/0x30 fs/file_table.c:497
task_work_run+0x130/0x1a0 kernel/task_work.c:233
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
__exit_to_user_mode_loop kernel/entry/common.c:67 [inline]
exit_to_user_mode_loop+0x1f4/0x6f0 kernel/entry/common.c:98
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
do_syscall_64+0x249/0x370 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811df94bac of 4 bytes by task 6867 on cpu 1:
pipe_lock+0x17/0x50 fs/pipe.c:90
splice_file_to_pipe+0x2e/0x390 fs/splice.c:1287
do_splice+0xc46/0x10b0 fs/splice.c:1374
__do_splice fs/splice.c:1431 [inline]
__do_sys_splice fs/splice.c:1634 [inline]
__se_sys_splice+0x26c/0x3a0 fs/splice.c:1616
__x64_sys_splice+0x78/0x90 fs/splice.c:1616
x64_sys_call+0x16ef/0x3020 arch/x86/include/generated/asm/syscalls_64.h:276
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000002 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 6867 Comm: syz.2.1159 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
==================================================================


---
This report 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 issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

If the report is already addressed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want to overwrite report's subsystems, reply with:
#syz set subsystems: new-subsystem
(See the list of subsystem names on the web dashboard)

If the report is a duplicate of another one, reply with:
#syz dup: exact-subject-of-another-report

If you want to undo deduplication, reply with:
#syz undup