syzbot


INFO: task hung in br_ioctl_stub (2)

Status: upstream: reported syz repro on 2025/12/01 17:08
Subsystems: bridge
[Documentation on labels]
Reported-by: syzbot+6bdeba54c73aa6a6219d@syzkaller.appspotmail.com
First crash: 5d17h, last: 5d17h
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [bridge?] INFO: task hung in br_ioctl_stub (2) 0 (1) 2025/12/01 17:08
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in br_ioctl_stub bridge 1 1 430d 430d 0/29 auto-obsoleted due to no activity on 2024/12/27 18:28
upstream INFO: task hung in rtnetlink_rcv_msg net 1 C inconclusive inconclusive 1970 512d 2475d 26/29 fixed on 2024/07/09 19:14
linux-5.15 INFO: task hung in br_ioctl_stub 1 2 518d 518d 0/3 auto-obsoleted due to no activity on 2024/10/11 06:35

Sample crash report:
INFO: task syz.0.27:5720 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.0.27        state:D stack:28904 pid:5720  tgid:5719  ppid:5469   task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760
 br_ioctl_stub+0x199/0xc80 net/bridge/br_ioctl.c:418
 br_ioctl_call net/socket.c:1227 [inline]
 sock_ioctl+0x4d8/0x790 net/socket.c:1329
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f91bf78f7c9
RSP: 002b:00007f91c0675038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f91bf9e5fa0 RCX: 00007f91bf78f7c9
RDX: 0000200000000000 RSI: 00000000000089a2 RDI: 0000000000000003
RBP: 00007f91bf813f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f91bf9e6038 R14: 00007f91bf9e5fa0 R15: 00007ffd440d2c68
 </TASK>
INFO: task kworker/u4:11:5722 blocked for more than 150 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:11   state:D stack:28872 pid:5722  tgid:5722  ppid:2      task_flags:0x4208060 flags:0x00080000
Workqueue: events_unbound linkwatch_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5325 [inline]
 __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929
 __schedule_loop kernel/sched/core.c:7011 [inline]
 schedule+0x165/0x360 kernel/sched/core.c:7026
 schedule_preempt_disabled+0x13/0x30 kernel/sched/core.c:7083
 __mutex_lock_common kernel/locking/mutex.c:676 [inline]
 __mutex_lock+0x7e6/0x1350 kernel/locking/mutex.c:760

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/27 17:00 upstream 765e56e41a5a e8331348 .config console log report syz / log [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root INFO: task hung in br_ioctl_stub
* Struck through repros no longer work on HEAD.