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INFO: task hung in rtnetlink_rcv_msg (2)

Status: premoderation: reported on 2026/01/21 16:59
Reported-by: syzbot+c8594a8ad43127762feb@syzkaller.appspotmail.com
First crash: 12d, last: 1d12h
▶ ▼ Similar bugs (16)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 INFO: task hung in rtnetlink_rcv_msg 1 1 934d 934d 0/3 auto-obsoleted due to no activity on 2023/10/22 21:13
linux-4.19 INFO: task hung in rtnetlink_rcv_msg (2) 1 14 1476d 1656d 0/1 auto-closed as invalid on 2022/05/18 11:30
linux-4.19 INFO: task hung in rtnetlink_rcv_msg (3) 1 8 1089d 1323d 0/1 upstream: reported on 2022/06/20 23:55
linux-4.19 INFO: task hung in rtnetlink_rcv_msg 1 11 1908d 2230d 0/1 auto-closed as invalid on 2021/03/12 19:03
upstream INFO: task hung in rtnetlink_rcv_msg (2) net 1 C inconclusive 548 315d 524d 0/29 closed as invalid on 2025/04/18 16:40
linux-6.1 INFO: task hung in rtnetlink_rcv_msg (3) origin:upstream 1 C error 20 22d 501d 0/3 upstream: reported C repro on 2024/09/19 14:16
linux-5.15 INFO: task hung in rtnetlink_rcv_msg (3) 1 1 292d 292d 0/3 auto-obsoleted due to no activity on 2025/07/26 04:34
upstream INFO: task hung in rtnetlink_rcv_msg net 1 C inconclusive inconclusive 1970 574d 2537d 26/29 fixed on 2024/07/09 19:14
linux-4.14 INFO: task hung in rtnetlink_rcv_msg 1 1 1069d 1069d 0/1 upstream: reported on 2023/03/01 21:15
linux-5.15 INFO: task hung in rtnetlink_rcv_msg (2) 1 70 444d 736d 0/3 auto-obsoleted due to no activity on 2025/01/24 13:11
linux-6.1 INFO: task hung in rtnetlink_rcv_msg (2) 1 67 574d 738d 0/3 auto-obsoleted due to no activity on 2024/09/17 07:45
linux-6.1 INFO: task hung in rtnetlink_rcv_msg 1 1 859d 859d 0/3 auto-obsoleted due to no activity on 2024/01/09 18:18
android-6-12 INFO: task hung in rtnetlink_rcv_msg 1 265 81d 227d 0/1 auto-obsoleted due to no activity on 2026/01/02 16:22
linux-6.6 INFO: task hung in rtnetlink_rcv_msg 1 3 4h15m 92d 0/2 upstream: reported on 2025/11/02 14:58
upstream INFO: task hung in rtnetlink_rcv_msg (3) net 1 4 242d 283d 0/29 auto-obsoleted due to no activity on 2025/09/03 19:16
upstream INFO: task hung in cangw_pernet_exit (3) can 1 syz unreliable 290 1498d 1604d 0/29 closed as invalid on 2022/02/08 10:22

Sample crash report:
INFO: task syz-executor:862 blocked for more than 122 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor    state:D stack:0     pid:862   tgid:862   ppid:1      flags:0x00004004
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5996 [inline]
 __schedule+0x134f/0x1ea0 kernel/sched/core.c:7843
 __schedule_loop kernel/sched/core.c:7924 [inline]
 schedule+0xc5/0x240 kernel/sched/core.c:7939
 schedule_preempt_disabled+0x14/0x30 kernel/sched/core.c:7996
 __mutex_lock_common kernel/locking/mutex.c:707 [inline]
 __mutex_lock+0x960/0x1bb0 kernel/locking/mutex.c:803
 __mutex_lock_slowpath+0xe/0x20 kernel/locking/mutex.c:1134
 mutex_lock+0x113/0x1d0 kernel/locking/mutex.c:285
 rtnl_lock net/core/rtnetlink.c:79 [inline]
 rtnetlink_rcv_msg+0x79e/0xa40 net/core/rtnetlink.c:6672
 netlink_rcv_skb+0x256/0x4f0 net/netlink/af_netlink.c:2545
 rtnetlink_rcv+0x20/0x30 net/core/rtnetlink.c:6693
 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
 netlink_unicast+0x8c0/0xa60 net/netlink/af_netlink.c:1339
 netlink_sendmsg+0x7fe/0xb10 net/netlink/af_netlink.c:1889
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 __sys_sendto+0x718/0x790 net/socket.c:2217
 __do_sys_sendto net/socket.c:2229 [inline]
 __se_sys_sendto net/socket.c:2225 [inline]
 __x64_sys_sendto+0xe9/0x100 net/socket.c:2225
 x64_sys_call+0x2c2c/0x2ee0 arch/x86/include/generated/asm/syscalls_64.h:45
 do_syscall_x64 arch/x86/entry/common.c:47 [inline]
 do_syscall_64+0x57/0xf0 arch/x86/entry/common.c:78
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fb5dcf560d7
RSP: 002b:00007ffd7ddf9b70 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 000055556536d500 RCX: 00007fb5dcf560d7
RDX: 0000000000000028 RSI: 00007fb5ddd44670 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffd7ddf9bd4 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000003
R13: 0000000000000000 R14: 00007fb5ddd44670 R15: 0000000000000000
 </TASK>
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 37 Comm: khungtaskd Not tainted syzkaller #0 001c7e68fa735976e9f6b7ad125989e1d2b10b0e
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:94
 dump_stack_lvl+0x140/0x1c0 lib/dump_stack.c:120
 dump_stack+0x19/0x20 lib/dump_stack.c:129
 nmi_cpu_backtrace+0x2ba/0x2d0 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x142/0x2c0 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:41
 trigger_all_cpu_backtrace include/linux/nmi.h:158 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:267 [inline]
 watchdog+0xdad/0xf00 kernel/hung_task.c:423
 kthread+0x2c9/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 33 Comm: rcuop/1 Not tainted syzkaller #0 001c7e68fa735976e9f6b7ad125989e1d2b10b0e
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:stack_trace_consume_entry+0x4b/0x2a0 kernel/stacktrace.c:86
Code: 47 10 4c 89 c3 48 c1 eb 03 0f b6 04 13 84 c0 0f 85 14 01 00 00 44 8b 57 10 4c 8d 4f 08 4d 89 cd 49 c1 ed 03 41 0f b6 44 15 00 <84> c0 0f 85 2d 01 00 00 45 3b 11 73 3c 4c 8d 67 0c 4d 89 e7 49 c1
RSP: 0018:ffffc90000007510 EFLAGS: 00000a06
RAX: 0000000000000000 RBX: 1ffff92000000ec6 RCX: 0000000000007500
RDX: dffffc0000000000 RSI: ffffffff81df5c9a RDI: ffffc90000007620
RBP: ffffc90000007558 R08: ffffc90000007630 R09: ffffc90000007628
R10: 0000000000000001 R11: ffffffff8175cb90 R12: ffff888103679300
R13: 1ffff92000000ec5 R14: ffffffff8175cb90 R15: ffffc90000007568
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fab45216038 CR3: 000000010c3c6000 CR4: 00000000003526b0
Call Trace:
 <IRQ>
 arch_stack_walk+0x12c/0x170 arch/x86/kernel/stacktrace.c:27
 stack_trace_save+0xaa/0x100 kernel/stacktrace.c:122
 kasan_save_stack mm/kasan/common.c:49 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:70
 kasan_save_free_info+0x4a/0x60 mm/kasan/generic.c:579
 poison_slab_object mm/kasan/common.c:249 [inline]
 __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:266
 kasan_slab_free include/linux/kasan.h:234 [inline]
 slab_free_hook mm/slub.c:2445 [inline]
 slab_free mm/slub.c:4714 [inline]
 kmem_cache_free+0x1bd/0x4f0 mm/slub.c:4821
 kfree_skbmem net/core/skbuff.c:-1 [inline]
 __kfree_skb+0x18f/0x210 net/core/skbuff.c:1203
 sk_skb_reason_drop+0xd8/0x310 net/core/skbuff.c:1240
 kfree_skb_reason include/linux/skbuff.h:1271 [inline]
 kfree_skb include/linux/skbuff.h:1280 [inline]
 ip6_mc_input+0x516/0x6c0 net/ipv6/ip6_input.c:587
 dst_input include/net/dst.h:469 [inline]
 ip6_rcv_finish+0x363/0x3e0 net/ipv6/ip6_input.c:79
 NF_HOOK include/linux/netfilter.h:317 [inline]
 ipv6_rcv+0xf1/0x240 net/ipv6/ip6_input.c:309
 __netif_receive_skb_one_core net/core/dev.c:5763 [inline]
 __netif_receive_skb net/core/dev.c:5876 [inline]
 process_backlog+0x44b/0xad0 net/core/dev.c:6212
 __napi_poll+0xd3/0x610 net/core/dev.c:6863
 napi_poll net/core/dev.c:6932 [inline]
 net_rx_action+0x5ea/0xd80 net/core/dev.c:7054
 handle_softirqs+0x1aa/0x630 kernel/softirq.c:621
 __do_softirq+0xf/0x16 kernel/softirq.c:659
 do_softirq+0xb8/0x110 kernel/softirq.c:503
 </IRQ>
 <TASK>
 __local_bh_enable_ip+0x74/0x80 kernel/softirq.c:430
 local_bh_enable include/linux/bottom_half.h:33 [inline]
 rcu_do_batch+0x5d9/0xd40 kernel/rcu/tree.c:2594
 nocb_cb_wait kernel/rcu/tree_nocb.h:923 [inline]
 rcu_nocb_cb_kthread+0x524/0xb30 kernel/rcu/tree_nocb.h:957
 kthread+0x2c9/0x370 kernel/kthread.c:389
 ret_from_fork+0x67/0xa0 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
net_ratelimit: 158548 callbacks suppressed
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:ae:71:d8:17:8f:14, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:1b, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on bridge_slave_0 with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)
bridge0: received packet on veth0_to_bridge with own address as source address (addr:aa:aa:aa:aa:aa:0c, vlan:0)

Crashes (11):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/01 20:15 android16-6.12 c13babfee861 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/02/01 13:07 android16-6.12 c13babfee861 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/02/01 00:29 android16-6.12 c13babfee861 6b8752f2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/01/31 19:41 android16-6.12 c13babfee861 afc0c4d4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/01/30 03:15 android16-6.12 d60ccb82b419 bfa73b7b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/01/29 14:09 android16-6.12 6acc5550e55c aeb6fdd5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/01/29 05:41 android16-6.12 bee827455b83 0adc945e .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/01/27 08:11 android16-6.12 0a08bd027b15 efb3e894 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/01/26 17:44 android16-6.12 132542afc0ef a4c52dd6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/01/25 23:36 android16-6.12 9ca0fde2622c 55756628 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
2026/01/21 16:59 android16-6.12 f33ca06267f8 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust INFO: task hung in rtnetlink_rcv_msg
* Struck through repros no longer work on HEAD.