[moderation] [serial?] KCSAN: data-race in __tty_hangup / filp_flush

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a1b5bd45d4ee Merge tag 'usb-6.15-rc1' of git://git.kernel...
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=143ffc3f980000
kernel config: https://syzkaller.appspot.com/x/.config?x=878fb2f189a26734
dashboard link: https://syzkaller.appspot.com/bug?extid=05bc8aebf378cee2fd49
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [gre...@linuxfoundation.org jiri...@kernel.org linux-...@vger.kernel.org linux-...@vger.kernel.org]

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/00434f294d96/disk-a1b5bd45.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/16c6fe422c4e/vmlinux-a1b5bd45.xz
kernel image: https://storage.googleapis.com/syzbot-assets/2b026f57c510/bzImage-a1b5bd45.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+05bc8a...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __tty_hangup / filp_flush

write to 0xffff888103acc248 of 8 bytes by task 19859 on cpu 1:
__tty_hangup+0x1d6/0x530 drivers/tty/tty_io.c:615
tty_vhangup+0x17/0x20 drivers/tty/tty_io.c:694
pty_close+0x260/0x280 drivers/tty/pty.c:79
tty_release+0x204/0x940 drivers/tty/tty_io.c:1754
__fput+0x2ac/0x640 fs/file_table.c:465
____fput+0x1c/0x30 fs/file_table.c:493
task_work_run+0x13c/0x1b0 kernel/task_work.c:227
get_signal+0xee2/0x1080 kernel/signal.c:2807
arch_do_signal_or_restart+0x9a/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:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x62/0x120 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888103acc248 of 8 bytes by task 19863 on cpu 0:
filp_flush+0x51/0x120 fs/open.c:1540
filp_close+0x1e/0x40 fs/open.c:1554
close_files fs/file.c:479 [inline]
put_files_struct+0x120/0x210 fs/file.c:494
exit_files+0x65/0x80 fs/file.c:511
do_exit+0x584/0x17e0 kernel/exit.c:948
do_group_exit+0x102/0x150 kernel/exit.c:1102
get_signal+0xf35/0x1080 kernel/signal.c:3034
arch_do_signal_or_restart+0x9a/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:329 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x62/0x120 kernel/entry/common.c:218
do_syscall_64+0xd6/0x1c0 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffffff8589e418 -> 0xffffffff8589e2b0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 19863 Comm: syz.8.5692 Not tainted 6.14.0-syzkaller-12886-ga1b5bd45d4ee #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================


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[syzbot]

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