syzbot


KCSAN: data-race in smc_poll / smc_setsockopt

Status: moderation: reported on 2026/03/05 11:37
Subsystems: smc
[Documentation on labels]
Reported-by: syzbot+f1b352aab0480d89dea5@syzkaller.appspotmail.com
First crash: 30d, last: 30d
✨ AI Jobs (3)
ID Workflow Result Correct Bug Created Started Finished Revision Error
62ab107a-3a32-41a1-8166-965694e5665c repro KCSAN: data-race in smc_poll / smc_setsockopt 2026/03/08 06:32 2026/03/08 06:32 2026/03/08 06:39 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
2f5af52a-ef45-45ab-afcb-acad7e92543b assessment-kcsan Benign: ✅  Confident: ✅  KCSAN: data-race in smc_poll / smc_setsockopt 2026/02/24 22:34 2026/02/24 22:34 2026/02/24 22:37 305c0ec5cd886e2d13738e28e1b2df9b0ec20fc9
c0529aa7-929a-4371-b91f-e96c6d8e4984 assessment-kcsan 💥 KCSAN: data-race in smc_poll / smc_setsockopt 2026/02/08 18:54 2026/02/08 18:54 2026/02/08 18:59 97745f52f5b9361548048f53f0b3b51b9313fedf fork/exec ./syz-agent: no such file or directory

Sample crash report:
==================================================================
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
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/08 18:54 upstream e98f34af6116 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in smc_poll / smc_setsockopt
* Struck through repros no longer work on HEAD.