[syzbot] [net?] INFO: task hung in genl_rcv_msg (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8d3ae59288f1 Linux 7.2
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17b70679580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4c9eb8e593cf8c5c
dashboard link: https://syzkaller.appspot.com/bug?extid=2ad5f42cd6ca88f0107c
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13913949580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17d6a679580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e3213198af93/disk-8d3ae592.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ccb0eb1c86ad/vmlinux-8d3ae592.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8c009fbdf753/bzImage-8d3ae592.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ad5f4...@syzkaller.appspotmail.com

INFO: task syz-executor328:5631 blocked for more than 143 seconds.
Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor328 state:D stack:24144 pid:5631 tgid:5631 ppid:5627 task_flags:0x400140 flags:0x00080000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5510 [inline]
__schedule+0x16dc/0x5500 kernel/sched/core.c:7234
__schedule_loop kernel/sched/core.c:7311 [inline]
rt_mutex_schedule+0x76/0xf0 kernel/sched/core.c:7607
rt_mutex_slowlock_block+0x55c/0x680 kernel/locking/rtmutex.c:1670
__rt_mutex_slowlock kernel/locking/rtmutex.c:1747 [inline]
__rt_mutex_slowlock_locked kernel/locking/rtmutex.c:1787 [inline]
rt_mutex_slowlock+0x2d4/0x780 kernel/locking/rtmutex.c:1827
__rt_mutex_lock kernel/locking/rtmutex.c:1842 [inline]
__mutex_lock_common kernel/locking/rtmutex_api.c:560 [inline]
mutex_lock_nested+0x168/0x1d0 kernel/locking/rtmutex_api.c:578
genl_lock net/netlink/genetlink.c:35 [inline]
genl_op_lock net/netlink/genetlink.c:60 [inline]
genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1208
netlink_rcv_skb+0x226/0x4a0 net/netlink/af_netlink.c:2556
genl_rcv+0x28/0x40 net/netlink/genetlink.c:1218
netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline]
netlink_unicast+0x7f5/0x990 net/netlink/af_netlink.c:1345
netlink_sendmsg+0x813/0xb40 net/netlink/af_netlink.c:1900
sock_sendmsg_nosec+0x13a/0x180 net/socket.c:775
__sock_sendmsg net/socket.c:790 [inline]
__sys_sendto+0x41e/0x5d0 net/socket.c:2252
__do_sys_sendto net/socket.c:2259 [inline]
__se_sys_sendto net/socket.c:2255 [inline]
__x64_sys_sendto+0xde/0x100 net/socket.c:2255
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f3a6b484867
RSP: 002b:00007ffc18787540 EFLAGS: 00000202 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00005555865654c0 RCX: 00007f3a6b484867
RDX: 0000000000000024 RSI: 00007f3a6b4f4b50 RDI: 0000000000000003
RBP: 0000000000000001 R08: 00007ffc18787594 R09: 000000000000000c
R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 00007f3a6b4f4b50
</TASK>

Showing all locks held in the system:
2 locks held by kworker/0:0/9:
9 locks held by ksoftirqd/0/15:
4 locks held by pr/legacy/17:
6 locks held by ktimers/1/29:
1 lock held by khungtaskd/38:
#0: ffffffff8e1c3040 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
#0: ffffffff8e1c3040 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:840 [inline]
#0: ffffffff8e1c3040 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180 kernel/locking/lockdep.c:6775
1 lock held by kcompactd0/41:
1 lock held by kcompactd1/42:
4 locks held by kworker/u8:5/67:
3 locks held by kworker/u8:7/154:
#0: ffff888032738138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff888032738138 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc900039bfc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc900039bfc40 ((work_completion)(&(&ifa->dad_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#2: ffffffff8f5ac938 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#2: ffffffff8f5ac938 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_dad_work+0x123/0x16e0 net/ipv6/addrconf.c:4229
6 locks held by kworker/u8:8/1014:
6 locks held by kworker/u8:9/1034:
#0: ffff88813ff5c138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff88813ff5c138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc90004aa7c40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc90004aa7c40 ((work_completion)(&rdev->wiphy_work)){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#2: ffff888040d208d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6884 [inline]
#2: ffff888040d208d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: cfg80211_wiphy_work+0xb4/0x420 net/wireless/core.c:524
#3: ffffffff8e059260 (local_bh){.+.+}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#4: ffffffff8e1c3040 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#5: ffff888040d20228 (&rdev->bss_lock){+...}-{3:3}, at: spin_lock_bh include/linux/spinlock_rt.h:90 [inline]
#5: ffff888040d20228 (&rdev->bss_lock){+...}-{3:3}, at: cfg80211_inform_single_bss_data+0xc22/0x1bf0 net/wireless/scan.c:2377
7 locks held by kworker/u8:11/1506:
6 locks held by kworker/u8:14/3336:
4 locks held by kworker/u8:15/3359:
#0: ffff88801aea0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff88801aea0938 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc9000ea07c40 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc9000ea07c40 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#2: ffffffff8f59dda0 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0xf5/0x810 net/core/net_namespace.c:673
#3: ffffffff8f5ac938 (rtnl_mutex){+.+.}-{4:4}, at: ieee80211_unregister_hw+0x55/0x2c0 net/mac80211/main.c:1711
2 locks held by klogd/4941:
#0: ffffffff8e1c3040 (rcu_read_lock){....}-{1:3}, at: __local_bh_disable_ip+0x3c/0x420 kernel/softirq.c:163
#1: ffff8880b86241a8 (tasklet_sync_callback.cb_lock){+...}-{3:3}, at: spin_lock include/linux/spinlock_rt.h:45 [inline]
#1: ffff8880b86241a8 (tasklet_sync_callback.cb_lock){+...}-{3:3}, at: tasklet_lock_callback kernel/softirq.c:877 [inline]
#1: ffff8880b86241a8 (tasklet_sync_callback.cb_lock){+...}-{3:3}, at: tasklet_action_common+0xc5/0x600 kernel/softirq.c:927
2 locks held by getty/5341:
#0: ffff8880366ae0a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70 drivers/tty/tty_ldisc.c:243
#1: ffffc90003cc62e0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x460/0x1360 drivers/tty/n_tty.c:2211
1 lock held by syz-executor328/5628:
#0: ffffffff8f5ac938 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_net_lock include/linux/rtnetlink.h:130 [inline]
#0: ffffffff8f5ac938 (rtnl_mutex){+.+.}-{4:4}, at: devinet_ioctl+0x2fb/0x1c50 net/ipv4/devinet.c:1120
4 locks held by syz-executor328/5629:
#0: ffffffff8f61dca0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8f61dab8 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
#1: ffffffff8f61dab8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
#1: ffffffff8f61dab8 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1208
#2: ffffffff8f5ac938 (rtnl_mutex){+.+.}-{4:4}, at: wiphy_register+0x1faf/0x2ff0 net/wireless/core.c:1154
#3: ffff88803c9108d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6884 [inline]
#3: ffff88803c9108d8 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: reg_process_self_managed_hints+0x8d/0x160 net/wireless/reg.c:3195
2 locks held by syz-executor328/5631:
#0: ffffffff8f61dca0 (cb_lock){++++}-{4:4}, at: genl_rcv+0x19/0x40 net/netlink/genetlink.c:1217
#1: ffffffff8f61dab8 (genl_mutex){+.+.}-{4:4}, at: genl_lock net/netlink/genetlink.c:35 [inline]
#1: ffffffff8f61dab8 (genl_mutex){+.+.}-{4:4}, at: genl_op_lock net/netlink/genetlink.c:60 [inline]
#1: ffffffff8f61dab8 (genl_mutex){+.+.}-{4:4}, at: genl_rcv_msg+0x10b/0x7a0 net/netlink/genetlink.c:1208
4 locks held by syz-executor328/5637:
3 locks held by kworker/0:3/5642:
#0: ffff88813ff1e538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#0: ffff88813ff1e538 ((wq_completion)events_power_efficient){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#1: ffffc9000458fc40 ((reg_check_chans).work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3297 [inline]
#1: ffffc9000458fc40 ((reg_check_chans).work){+.+.}-{0:0}, at: process_scheduled_works+0xa20/0x14e0 kernel/workqueue.c:3405
#2: ffffffff8f5ac938 (rtnl_mutex){+.+.}-{4:4}, at: reg_check_chans_work+0xac/0x1110 net/wireless/reg.c:2469

=============================================

NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 38 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
<TASK>
dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
nmi_cpu_backtrace+0x274/0x2d0 lib/nmi_backtrace.c:122
nmi_trigger_cpumask_backtrace+0x17a/0x380 lib/nmi_backtrace.c:65
trigger_all_cpu_backtrace include/linux/nmi.h:162 [inline]
__sys_info lib/sys_info.c:157 [inline]
sys_info+0x135/0x170 lib/sys_info.c:165
check_hung_uninterruptible_tasks kernel/hung_task.c:353 [inline]
watchdog+0xfd7/0x1030 kernel/hung_task.c:561
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 1034 Comm: kworker/u8:9 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: events_unbound cfg80211_wiphy_work
RIP: 0010:check_kcov_mode kernel/kcov.c:183 [inline]
RIP: 0010:write_comp_data kernel/kcov.c:246 [inline]
RIP: 0010:__sanitizer_cov_trace_switch+0x92/0x110 kernel/kcov.c:351
Code: 39 c8 0f 84 86 00 00 00 4e 8b 5c ce 10 65 8b 2d f4 90 d8 10 81 e5 00 00 ff 00 41 8b 98 f4 0b 00 00 44 21 d3 41 89 de 41 09 ee <74> 12 85 ed 75 cc 85 db 74 c8 41 83 b8 0c 17 00 00 00 74 be 41 8b
RSP: 0018:ffffc90004aa64e0 EFLAGS: 00000246
RAX: 0000000000000020 RBX: 0000000000000000 RCX: 0000000000000005
RDX: ffffffff81c9fb3a RSI: ffffffff8e2264f0 RDI: 000000000000000a
RBP: 0000000000000000 R08: ffff8880275c3e00 R09: 0000000000000014
R10: 0000000000000100 R11: 0000000000000014 R12: 00000054f161582e
R13: 000000000000000a R14: 0000000000000000 R15: ffff88803210f664
FS: 0000000000000000(0000) GS:ffff888125d3a000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055d1b2826660 CR3: 000000000dfb0000 CR4: 00000000003526f0
Call Trace:
<TASK>
rb_read_data_buffer+0x14a/0x5b0 kernel/trace/ring_buffer.c:1861
check_buffer+0x288/0x7f0 kernel/trace/ring_buffer.c:4690
__rb_reserve_next+0x537/0xdc0 kernel/trace/ring_buffer.c:4791
rb_reserve_next_event kernel/trace/ring_buffer.c:4928 [inline]
ring_buffer_lock_reserve+0xbd5/0x1040 kernel/trace/ring_buffer.c:4987
__trace_buffer_lock_reserve kernel/trace/trace.h:1676 [inline]
trace_event_buffer_lock_reserve+0x1d2/0x700 kernel/trace/trace.c:1924
trace_event_buffer_reserve+0x1ef/0x2d0 kernel/trace/trace_events.c:688
do_trace_event_raw_event_lock_acquire include/trace/events/lock.h:23 [inline]
trace_event_raw_event_lock_acquire+0x12b/0x2e0 include/trace/events/lock.h:23
__do_trace_lock_acquire include/trace/events/lock.h:23 [inline]
trace_lock_acquire include/trace/events/lock.h:23 [inline]
lock_acquire+0x2ff/0x350 kernel/locking/lockdep.c:5831
rcu_lock_acquire include/linux/rcupdate.h:300 [inline]
rcu_read_lock include/linux/rcupdate.h:840 [inline]
class_rcu_constructor include/linux/rcupdate.h:1183 [inline]
unwind_next_frame+0xac/0x2550 arch/x86/kernel/unwind_orc.c:495
arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25
stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122
kasan_save_stack mm/kasan/common.c:57 [inline]
kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:415
kasan_kmalloc include/linux/kasan.h:263 [inline]
__do_kmalloc_node mm/slub.c:5334 [inline]
__kmalloc_noprof+0x41a/0x780 mm/slub.c:5359
_kmalloc_noprof include/linux/slab.h:992 [inline]
_kzalloc_noprof include/linux/slab.h:1309 [inline]
cfg80211_inform_single_bss_data+0x986/0x1bf0 net/wireless/scan.c:2354
cfg80211_inform_bss_data+0x25b/0x3d50 net/wireless/scan.c:3241
cfg80211_inform_bss_frame_data+0x3c7/0x840 net/wireless/scan.c:3333
ieee80211_bss_info_update+0x791/0xa50 net/mac80211/scan.c:230
ieee80211_rx_bss_info net/mac80211/ibss.c:1063 [inline]
ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1544 [inline]
ieee80211_ibss_rx_queued_mgmt+0x1ce3/0x2c40 net/mac80211/ibss.c:1571
ieee80211_iface_process_skb net/mac80211/iface.c:1769 [inline]
ieee80211_iface_work+0x78a/0x1010 net/mac80211/iface.c:1823
cfg80211_wiphy_work+0x29e/0x420 net/wireless/core.c:538
process_one_work kernel/workqueue.c:3322 [inline]
process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405
worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486
kthread+0x388/0x470 kernel/kthread.c:436
ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
</TASK>


---
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