syzbot


KCSAN: data-race in smc_connect_work / smc_poll

Status: moderation: reported on 2026/01/05 14:11
Subsystems: smc
[Documentation on labels]
Reported-by: syzbot+d117875e286a8282c351@syzkaller.appspotmail.com
First crash: 65d, last: 65d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in smc_connect_work / smc_poll

write to 0xffff88811a82089c of 4 bytes by task 3413 on cpu 0:
 smc_connect_work+0xef/0x4e0 net/smc/af_smc.c:1606
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346
 worker_thread+0x582/0x770 kernel/workqueue.c:3427
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

read to 0xffff88811a82089c of 4 bytes by task 24721 on cpu 1:
 smc_poll+0x188/0x530 net/smc/af_smc.c:2890
 sock_poll+0x20d/0x230 net/socket.c:1443
 vfs_poll include/linux/poll.h:82 [inline]
 select_poll_one fs/select.c:480 [inline]
 do_select+0x8f1/0xf40 fs/select.c:536
 core_sys_select+0x3dc/0x6e0 fs/select.c:677
 do_pselect fs/select.c:759 [inline]
 __do_sys_pselect6 fs/select.c:802 [inline]
 __se_sys_pselect6+0x216/0x280 fs/select.c:793
 __x64_sys_pselect6+0x78/0x90 fs/select.c:793
 x64_sys_call+0x28bd/0x3000 arch/x86/include/generated/asm/syscalls_64.h:271
 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: 0x00000000 -> 0x0000006f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 24721 Comm: syz.1.7092 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/08 07:40 upstream da32d155f4a8 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in smc_connect_work / smc_poll
* Struck through repros no longer work on HEAD.