[moderation] [serial?] KCSAN: data-race in __se_sys_ioctl / __tty_hangup (6)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 320475fbd590 Merge tag 'mtd/fixes-for-6.17-rc6' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=150deb62580000
kernel config: https://syzkaller.appspot.com/x/.config?x=6e0c213d0735f5dd
dashboard link: https://syzkaller.appspot.com/bug?extid=957cf71f23c540181661
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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/03d005b220b7/disk-320475fb.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3ce8904c800d/vmlinux-320475fb.xz
kernel image: https://storage.googleapis.com/syzbot-assets/04e70a318f85/bzImage-320475fb.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+957cf7...@syzkaller.appspotmail.com

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

write to 0xffff88811a27cf08 of 8 bytes by task 36 on cpu 1:
__tty_hangup+0x1ef/0x540 drivers/tty/tty_io.c:612
do_tty_hangup+0x1e/0x30 drivers/tty/tty_io.c:663
process_one_work kernel/workqueue.c:3236 [inline]
process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3319
worker_thread+0x582/0x770 kernel/workqueue.c:3400
kthread+0x489/0x510 kernel/kthread.c:463
ret_from_fork+0x11f/0x1b0 arch/x86/kernel/process.c:148
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811a27cf08 of 8 bytes by task 6598 on cpu 0:
vfs_ioctl fs/ioctl.c:48 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xa1/0x140 fs/ioctl.c:584
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584
x64_sys_call+0x1816/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0xffffffff858a1f90 -> 0xffffffff858a1e80

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 6598 Comm: syz.0.1047 Tainted: G W syzkaller #0 PREEMPT(voluntary)
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
==================================================================


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