syzbot


INFO: task hung in snd_seq_device_dev_free

Status: upstream: reported on 2025/12/05 08:54
Reported-by: syzbot+3c69865011697645f2e4@syzkaller.appspotmail.com
First crash: 10d, last: 10d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream INFO: task hung in snd_seq_device_dev_free sound 1 1 510d 510d 0/29 auto-obsoleted due to no activity on 2024/10/22 03:37

Sample crash report:
INFO: task kworker/1:4:4224 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/1:4     state:D stack:21216 pid: 4224 ppid:     2 flags:0x00004000
Workqueue: usb_hub_wq hub_event
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_timeout+0x97/0x280 kernel/time/timer.c:1890
 do_wait_for_common+0x29a/0x440 kernel/sched/completion.c:85
 __wait_for_common kernel/sched/completion.c:106 [inline]
 wait_for_common kernel/sched/completion.c:117 [inline]
 wait_for_completion+0x48/0x60 kernel/sched/completion.c:138
 __flush_work+0x120/0x1b0 kernel/workqueue.c:3094
 __cancel_work_timer+0x3ac/0x520 kernel/workqueue.c:3181
 cancel_autoload_drivers sound/core/seq_device.c:139 [inline]
 snd_seq_device_dev_free+0x40/0x90 sound/core/seq_device.c:158
 __snd_device_free+0x1cd/0x2e0 sound/core/device.c:76
 snd_device_free_all+0xcb/0x180 sound/core/device.c:233
 snd_card_do_free sound/core/init.c:588 [inline]
 release_card_device+0x6d/0x1f0 sound/core/init.c:145
 device_release+0x92/0x1c0 drivers/base/core.c:-1
 kobject_cleanup lib/kobject.c:713 [inline]
 kobject_release lib/kobject.c:744 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x21d/0x460 lib/kobject.c:761
 snd_card_free_when_closed+0x3d/0x50 sound/core/init.c:620
 usb_audio_disconnect+0x5dd/0x6e0 sound/usb/card.c:1005
 usb_unbind_interface+0x1ee/0x860 drivers/usb/core/driver.c:458
 __device_release_driver drivers/base/dd.c:1229 [inline]
 device_release_driver_internal+0x4b4/0x750 drivers/base/dd.c:1262
 bus_remove_device+0x2e2/0x400 drivers/base/bus.c:531
 device_del+0x628/0xa70 drivers/base/core.c:3600
 usb_disable_device+0x3e2/0x890 drivers/usb/core/message.c:1414
 usb_disconnect+0x348/0x8a0 drivers/usb/core/hub.c:2287
 hub_port_connect drivers/usb/core/hub.c:5341 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
 port_event drivers/usb/core/hub.c:5799 [inline]
 hub_event+0x1e9f/0x5560 drivers/usb/core/hub.c:5881
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 process_scheduled_works kernel/workqueue.c:2373 [inline]
 worker_thread+0xdca/0x12a0 kernel/workqueue.c:2459
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
INFO: task udevd:4301 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:udevd           state:D stack:24032 pid: 4301 ppid:  3562 flags:0x00004002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5049 [inline]
 __schedule+0x11bb/0x4390 kernel/sched/core.c:6395
 schedule+0x11b/0x1e0 kernel/sched/core.c:6478
 schedule_preempt_disabled+0xf/0x20 kernel/sched/core.c:6537
 __mutex_lock_common+0xc71/0x2390 kernel/locking/mutex.c:669
 __mutex_lock kernel/locking/mutex.c:729 [inline]
 mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
 device_lock include/linux/device.h:764 [inline]
 uevent_show+0x17a/0x330 drivers/base/core.c:2408
 dev_attr_show+0x50/0xb0 drivers/base/core.c:2110
 sysfs_kf_seq_show+0x316/0x4c0 fs/sysfs/file.c:61
 seq_read_iter+0x49b/0xd50 fs/seq_file.c:230
 call_read_iter include/linux/fs.h:2167 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0x725/0xcf0 fs/read_write.c:485
 ksys_read+0x14d/0x250 fs/read_write.c:623
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fbbc0cbd407
RSP: 002b:00007fffc452e330 EFLAGS: 00000202 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fbbc0bcf880 RCX: 00007fbbc0cbd407
RDX: 0000000000001000 RSI: 0000555ecbe50a00 RDI: 0000000000000008
RBP: 00007fbbc0e05ff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000202 R12: 000000000000000a
R13: 00007fbbc0e05ea0 R14: 0000000000000000 R15: 0000555ecbe65bf0
 </TASK>

Showing all locks held in the system:
2 locks held by kworker/1:0/21:
 #0: ffff888016870938 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90000db7d00 (autoload_work){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
1 lock held by khungtaskd/27:
 #0: ffffffff8c11c760 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire+0x0/0x30
2 locks held by kworker/u4:4/1238:
 #0: ffff888016879138 ((wq_completion)events_unbound){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc90004e47d00 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
1 lock held by dhcpcd/3855:
 #0: ffff88801686f828 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
 #0: ffff88801686f828 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x15d/0x2b0 mm/util.c:549
2 locks held by getty/3950:
 #0: ffff88802bc65098 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x21/0x70 drivers/tty/tty_ldisc.c:252
 #1: ffffc90002cf62e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x5ba/0x1a30 drivers/tty/n_tty.c:2158
1 lock held by syz-executor/4173:
 #0: ffff888079d3d528 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
 #0: ffff888079d3d528 (&mm->mmap_lock){++++}-{3:3}, at: vm_mmap_pgoff+0x15d/0x2b0 mm/util.c:549
5 locks held by kworker/1:4/4224:
 #0: ffff88801b755938 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x760/0x1000 kernel/workqueue.c:-1
 #1: ffffc9000306fd00 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x7a3/0x1000 kernel/workqueue.c:2285
 #2: ffff888023510220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #2: ffff888023510220 (&dev->mutex){....}-{3:3}, at: hub_event+0x1a7/0x5560 drivers/usb/core/hub.c:5827
 #3: ffff88802b05b220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #3: ffff88802b05b220 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x107/0x8a0 drivers/usb/core/hub.c:2278
 #4: ffff88805ea531a8 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #4: ffff88805ea531a8 (&dev->mutex){....}-{3:3}, at: __device_driver_lock drivers/base/dd.c:1044 [inline]
 #4: ffff88805ea531a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0xb0/0x750 drivers/base/dd.c:1259
4 locks held by udevd/4301:
 #0: ffff88801ded22f0 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xad/0xd50 fs/seq_file.c:182
 #1: ffff888078f87888 (&of->mutex){+.+.}-{3:3}, at: kernfs_seq_start+0x51/0x3c0 fs/kernfs/file.c:112
 #2: ffff8880209592c0 (kn->active#32){++++}-{0:0}, at: kernfs_seq_start+0x71/0x3c0 fs/kernfs/file.c:113
 #3: ffff88802b05b220 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:764 [inline]
 #3: ffff88802b05b220 (&dev->mutex){....}-{3:3}, at: uevent_show+0x17a/0x330 drivers/base/core.c:2408
1 lock held by modprobe/4497:
 #0: ffff888078e53228 (&mm->mmap_lock){++++}-{3:3}, at: mmap_write_lock_killable include/linux/mmap_lock.h:87 [inline]
 #0: ffff888078e53228 (&mm->mmap_lock){++++}-{3:3}, at: setup_arg_pages+0x2db/0xa20 fs/exec.c:797

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

NMI backtrace for cpu 1
CPU: 1 PID: 27 Comm: khungtaskd Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 nmi_cpu_backtrace+0x397/0x3d0 lib/nmi_backtrace.c:111
 nmi_trigger_cpumask_backtrace+0x163/0x280 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:148 [inline]
 check_hung_uninterruptible_tasks kernel/hung_task.c:212 [inline]
 watchdog+0xe0f/0xe50 kernel/hung_task.c:369
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 729 Comm: kworker/u4:3 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: phy10 ieee80211_iface_work
RIP: 0010:memset_erms+0xb/0x10 arch/x86/lib/memset_64.S:65
Code: 03 40 0f b6 f6 48 b8 01 01 01 01 01 01 01 01 48 0f af c6 f3 48 ab 89 d1 f3 aa 4c 89 c8 c3 90 49 89 f9 40 88 f0 48 89 d1 f3 aa <4c> 89 c8 c3 90 49 89 fa 40 0f b6 ce 48 b8 01 01 01 01 01 01 01 01
RSP: 0018:ffffc90003aef5a8 EFLAGS: 00000202
RAX: 0000000000000200 RBX: ffff88807a043800 RCX: 0000000000000000
RDX: 0000000000000200 RSI: 0000000000000000 RDI: ffffc90003aef7b0
RBP: ffffc90003aef7d0 R08: dffffc0000000000 R09: ffffc90003aef5b0
R10: 0000000000000000 R11: 0000000000000038 R12: ffff88807a043c00
R13: ffff88805f105b08 R14: 0000000000000b20 R15: ffffc90003aef5b0
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd9e9b3f18 CR3: 000000007e492000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kasan_save_stack mm/kasan/common.c:35 [inline]
 kasan_set_track mm/kasan/common.c:46 [inline]
 set_alloc_info mm/kasan/common.c:434 [inline]
 ____kasan_kmalloc mm/kasan/common.c:513 [inline]
 __kasan_kmalloc+0xa6/0xf0 mm/kasan/common.c:522
 kmalloc include/linux/slab.h:612 [inline]
 kzalloc include/linux/slab.h:738 [inline]
 ieee802_11_parse_elems_crc+0xab/0x10c0 net/mac80211/util.c:1478
 ieee802_11_parse_elems net/mac80211/ieee80211_i.h:2243 [inline]
 ieee80211_rx_mgmt_probe_beacon net/mac80211/ibss.c:1609 [inline]
 ieee80211_ibss_rx_queued_mgmt+0x369/0x29c0 net/mac80211/ibss.c:1643
 ieee80211_iface_process_skb net/mac80211/iface.c:1459 [inline]
 ieee80211_iface_work+0x70e/0xc60 net/mac80211/iface.c:1513
 process_one_work+0x863/0x1000 kernel/workqueue.c:2310
 worker_thread+0xaa8/0x12a0 kernel/workqueue.c:2457
 kthread+0x436/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/12/05 08:53 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan INFO: task hung in snd_seq_device_dev_free
* Struck through repros no longer work on HEAD.