[moderation] [io-uring?] KCSAN: data-race in io_submit_sqes / io_uring_poll (9)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: e98f34af6116 Merge tag 'i2c-for-6.19-final' of git://git.k..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1615a33a580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8e27f4588a0f2183
dashboard link: https://syzkaller.appspot.com/bug?extid=7ef14dc2fcc5d562bfa3
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [ax...@kernel.dk io-u...@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/49a5e6aae7b9/disk-e98f34af.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/605a872be1a9/vmlinux-e98f34af.xz
kernel image: https://storage.googleapis.com/syzbot-assets/dfd740d44724/bzImage-e98f34af.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7ef14d...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in io_submit_sqes / io_uring_poll

write to 0xffff88811b0b0804 of 2 bytes by task 3493 on cpu 0:
io_init_req io_uring/io_uring.c:2177 [inline]
io_submit_sqe io_uring/io_uring.c:2282 [inline]
io_submit_sqes+0xc11/0x11b0 io_uring/io_uring.c:2435
__do_sys_io_uring_enter io_uring/io_uring.c:3285 [inline]
__se_sys_io_uring_enter+0x1bf/0x1c70 io_uring/io_uring.c:3224
__x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3224
x64_sys_call+0x27e4/0x3000 arch/x86/include/generated/asm/syscalls_64.h:427
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b0b0804 of 2 bytes by task 3489 on cpu 1:
io_uring_poll+0x2f/0x1b0 io_uring/io_uring.c:2930
vfs_poll include/linux/poll.h:82 [inline]
__io_arm_poll_handler+0x1ee/0xb80 io_uring/poll.c:581
io_poll_add+0x69/0xf0 io_uring/poll.c:899
__io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1793
io_issue_sqe+0x20b/0xc20 io_uring/io_uring.c:1816
io_queue_sqe io_uring/io_uring.c:2043 [inline]
io_submit_sqe io_uring/io_uring.c:2321 [inline]
io_submit_sqes+0x78a/0x11b0 io_uring/io_uring.c:2435
__do_sys_io_uring_enter io_uring/io_uring.c:3285 [inline]
__se_sys_io_uring_enter+0x1bf/0x1c70 io_uring/io_uring.c:3224
__x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:3224
x64_sys_call+0x27e4/0x3000 arch/x86/include/generated/asm/syscalls_64.h:427
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0100 -> 0x0304

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3489 Comm: syz.2.3 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
==================================================================


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