[moderation] [serial?] KCSAN: data-race in n_tty_poll / tty_set_termios (8)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fac04efc5c79 Linux 6.13-rc2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1393c8f8580000
kernel config: https://syzkaller.appspot.com/x/.config?x=1fe4854f351e948c
dashboard link: https://syzkaller.appspot.com/bug?extid=f4d617d875e468233ebd
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/5b59ffa1ee4d/disk-fac04efc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2b25b47f9969/vmlinux-fac04efc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a7b8a70846c9/bzImage-fac04efc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+f4d617...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in n_tty_poll / tty_set_termios

write to 0xffff88813a4b5d1f of 1 bytes by task 10650 on cpu 0:
unset_locked_termios drivers/tty/tty_ioctl.c:220 [inline]
tty_set_termios+0x3ee/0x8b0 drivers/tty/tty_ioctl.c:340
set_termios+0x497/0x4e0 drivers/tty/tty_ioctl.c:516
tty_mode_ioctl+0x391/0x5d0
n_tty_ioctl_helper+0x8d/0x240 drivers/tty/tty_ioctl.c:986
n_tty_ioctl+0xfd/0x200 drivers/tty/n_tty.c:2521
tty_ioctl+0x87a/0xbe0 drivers/tty/tty_io.c:2812
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:906 [inline]
__se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
x64_sys_call+0x1690/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88813a4b5d1f of 1 bytes by task 10645 on cpu 1:
input_available_p drivers/tty/n_tty.c:1937 [inline]
n_tty_poll+0x256/0x490 drivers/tty/n_tty.c:2468
tty_poll+0x78/0xf0 drivers/tty/tty_io.c:2208
vfs_poll include/linux/poll.h:84 [inline]
io_file_supports_nowait io_uring/rw.c:43 [inline]
io_write+0x1b2/0xc40 io_uring/rw.c:1056
io_issue_sqe+0x150/0xc10 io_uring/io_uring.c:1736
io_queue_sqe io_uring/io_uring.c:1946 [inline]
io_submit_sqe io_uring/io_uring.c:2201 [inline]
io_submit_sqes+0x64d/0x1090 io_uring/io_uring.c:2318
__do_sys_io_uring_enter io_uring/io_uring.c:3390 [inline]
__se_sys_io_uring_enter+0x1b9/0x1ba0 io_uring/io_uring.c:3325
__x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3325
x64_sys_call+0xb5e/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:427
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x01 -> 0x33

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 10645 Comm: syz.4.2461 Not tainted 6.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
==================================================================


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[syzbot]

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