[moderation] [smc?] KCSAN: data-race in smc_poll / smc_setsockopt

[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=1510eb22580000
kernel config: https://syzkaller.appspot.com/x/.config?x=8e27f4588a0f2183
dashboard link: https://syzkaller.appspot.com/bug?extid=f1b352aab0480d89dea5
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
CC: [ali...@linux.alibaba.com da...@davemloft.net dus...@linux.alibaba.com edum...@google.com gu...@linux.alibaba.com ho...@kernel.org ku...@kernel.org linux-...@vger.kernel.org linux...@vger.kernel.org linux...@vger.kernel.org mjam...@linux.ibm.com net...@vger.kernel.org pab...@redhat.com sid...@linux.ibm.com ton...@linux.alibaba.com wen...@linux.ibm.com]

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+f1b352...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in smc_poll / smc_setsockopt

write to 0xffff88810a7b011c of 4 bytes by task 5103 on cpu 0:
smc_setsockopt+0x1d6/0x750 net/smc/af_smc.c:3100
do_sock_setsockopt net/socket.c:2322 [inline]
__sys_setsockopt+0x184/0x200 net/socket.c:2347
__do_sys_setsockopt net/socket.c:2353 [inline]
__se_sys_setsockopt net/socket.c:2350 [inline]
__x64_sys_setsockopt+0x64/0x80 net/socket.c:2350
x64_sys_call+0x21d5/0x3000 arch/x86/include/generated/asm/syscalls_64.h:55
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 0xffff88810a7b011c of 4 bytes by task 5102 on cpu 1:
smc_poll+0x188/0x530 net/smc/af_smc.c:2890
sock_poll+0x21c/0x240 net/socket.c:1443
vfs_poll include/linux/poll.h:82 [inline]
__io_arm_poll_handler+0x1ee/0xb80 io_uring/poll.c:581
io_arm_apoll+0x2eb/0x410 io_uring/poll.c:689
io_arm_poll_handler+0x131/0x160 io_uring/poll.c:718
io_queue_async+0x25d/0x2d0 io_uring/io_uring.c:2024
io_queue_sqe io_uring/io_uring.c:2050 [inline]
io_submit_sqe io_uring/io_uring.c:2321 [inline]
io_submit_sqes+0xb8f/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: 0x00000000 -> 0x0000006f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 5102 Comm: syz.1.586 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
==================================================================


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