syzbot


INFO: task hung in addrconf_dad_work

Status: upstream: reported syz repro on 2025/11/26 06:47
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+4bfb583ae9cc4f93097e@syzkaller.appspotmail.com
First crash: 64d, last: 64d
Bug presence (2)
Date Name Commit Repro Result
2025/11/30 linux-6.6.y (ToT) 1e89a1be4fe9 syz [report] INFO: task hung in new_device_store
2025/11/30 upstream (ToT) e69c7c175115 syz Didn't crash
Similar bugs (15)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 INFO: task hung in addrconf_dad_work (2) 1 67 498d 704d 0/3 auto-obsoleted due to no activity on 2024/11/26 11:15
android-414 INFO: task hung in addrconf_dad_work 1 1 2425d 2425d 0/1 auto-closed as invalid on 2019/10/25 08:37
upstream INFO: task hung in addrconf_dad_work (5) net 1 C done 1633 1d06h 548d 0/29 upstream: reported C repro on 2024/07/29 15:23
android-49 INFO: task hung in addrconf_dad_work 1 1 2712d 2712d 0/3 auto-closed as invalid on 2019/02/22 20:09
upstream INFO: task hung in addrconf_dad_work (2) net 1 C unreliable error 107 798d 1152d 0/29 closed as invalid on 2023/11/23 17:05
linux-6.1 INFO: task hung in addrconf_dad_work (4) origin:upstream missing-backport 1 syz error 5 31d 244d 0/3 upstream: reported syz repro on 2025/05/29 09:13
linux-6.1 INFO: task hung in addrconf_dad_work 1 2 987d 1017d 0/3 auto-obsoleted due to no activity on 2023/08/26 05:16
upstream INFO: task hung in addrconf_dad_work net 1 C inconclusive inconclusive 468 1498d 2538d 0/29 closed as invalid on 2022/02/08 10:54
linux-5.15 INFO: task hung in addrconf_dad_work origin:upstream 1 C 131 20d 740d 0/3 upstream: reported C repro on 2024/01/20 08:09
upstream INFO: task hung in addrconf_dad_work (3) net 1 C 185 687d 729d 25/29 fixed on 2024/03/25 23:45
linux-6.1 INFO: task hung in addrconf_dad_work (3) 1 2 357d 389d 0/3 auto-obsoleted due to no activity on 2025/05/16 13:56
linux-4.19 INFO: task hung in addrconf_dad_work 1 1 2347d 2347d 0/1 auto-closed as invalid on 2019/12/24 18:36
linux-4.19 INFO: task hung in addrconf_dad_work (2) 1 C error 72 1065d 2138d 0/1 upstream: reported C repro on 2020/03/22 17:39
linux-4.14 INFO: task hung in addrconf_dad_work 1 C inconclusive 1 1313d 1919d 0/1 upstream: reported C repro on 2020/10/27 17:48
upstream INFO: task hung in addrconf_dad_work (4) net 1 2632 568d 619d 26/29 fixed on 2024/07/09 19:14
Fix bisection attempts (1)
Created Duration User Patch Repo Result
2026/01/21 06:43 1m fix candidate upstream error job log

Sample crash report:
INFO: task kworker/u4:2:42 blocked for more than 141 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:2    state:D stack:24400 pid:42    ppid:2      flags:0x00004000
Workqueue: ipv6_addrconf addrconf_dad_work
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 addrconf_dad_work+0xd0/0x14e0 net/ipv6/addrconf.c:4158
 process_one_work kernel/workqueue.c:2634 [inline]
 process_scheduled_works+0xa45/0x15b0 kernel/workqueue.c:2711
 worker_thread+0xa55/0xfc0 kernel/workqueue.c:2792
 kthread+0x2fa/0x390 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293
 </TASK>
INFO: task syz-executor:5925 blocked for more than 151 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:21192 pid:5925  ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5380 [inline]
 __schedule+0x14d2/0x44d0 kernel/sched/core.c:6699
 schedule+0xbd/0x170 kernel/sched/core.c:6773
 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6832
 __mutex_lock_common kernel/locking/mutex.c:679 [inline]
 __mutex_lock+0x6b7/0xcc0 kernel/locking/mutex.c:747
 rtnl_lock net/core/rtnetlink.c:78 [inline]
 rtnetlink_rcv_msg+0x76f/0xf10 net/core/rtnetlink.c:6469
 netlink_rcv_skb+0x216/0x480 net/netlink/af_netlink.c:2545
 netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline]
 netlink_unicast+0x751/0x8d0 net/netlink/af_netlink.c:1346
 netlink_sendmsg+0x8c1/0xbe0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x46a/0x620 net/socket.c:2201

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/11/26 06:46 linux-6.6.y 1e89a1be4fe9 64219f15 .config console log report syz / log [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan INFO: task hung in addrconf_dad_work
* Struck through repros no longer work on HEAD.