syzbot


INFO: task hung in usb_bulk_msg (2)

Status: upstream: reported C repro on 2026/02/08 06:34
Subsystems: usb
[Documentation on labels]
Reported-by: syzbot+25ba18e2c5040447585d@syzkaller.appspotmail.com
Fix commit: 7784caa413a8 USB: usbtmc: Use usb_bulk_msg_killable() with user-specified timeouts
Patched on: [ci-qemu-gce-upstream-auto ci-qemu-native-arm64-kvm ci-qemu-upstream ci-qemu-upstream-386 ci-qemu2-arm32 ci-qemu2-arm64 ci-qemu2-arm64-compat ci-qemu2-arm64-mte ci-qemu2-riscv64 ci-snapshot-upstream-root ci-upstream-bpf-kasan-gce ci-upstream-bpf-next-kasan-gce ci-upstream-gce-leak ci-upstream-kasan-badwrites-root ci-upstream-kasan-gce ci-upstream-kasan-gce-386 ci-upstream-kasan-gce-root ci-upstream-kasan-gce-selinux-root ci-upstream-kasan-gce-smack-root ci-upstream-kmsan-gce-386-root ci-upstream-kmsan-gce-root ci-upstream-linux-next-kasan-gce-root ci-upstream-net-kasan-gce ci-upstream-net-this-kasan-gce ci-upstream-rust-kasan-gce ci2-upstream-fs ci2-upstream-kcsan-gce ci2-upstream-usb], missing on: [ci-upstream-gce-arm64]
First crash: 58d, last: 28d
Discussions (4)
Title Replies (including bot) Last reply
[PATCH v3 2/3] USB: usbtmc: Use usb_bulk_msg_killable() with user-specified timeouts 1 (1) 2026/02/18 03:09
[PATCH v2 2/3] USB: usbtmc: Use usb_bulk_msg_killable() with user-specified timeouts 1 (1) 2026/02/17 16:23
[syzbot] [usb?] INFO: task hung in usb_bulk_msg (2) 11 (21) 2026/02/13 21:49
[PATCH 2/2] USB: usbtmc: Don't accept very long timeouts 2 (2) 2026/02/10 09:03
Similar bugs (3)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 INFO: task hung in usb_bulk_msg 1 C 88 1130d 2483d 0/1 upstream: reported C repro on 2019/06/20 04:21
upstream INFO: task hung in usb_bulk_msg usb 1 C error unreliable 557 1614d 2769d 0/29 auto-obsoleted due to no activity on 2022/10/02 23:39
linux-4.19 INFO: task hung in usb_bulk_msg 1 C error 213 1134d 2549d 0/1 upstream: reported C repro on 2019/04/15 07:30
Last patch testing requests (14)
Created Duration User Patch Repo Result
2026/03/09 16:06 16m retest repro https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing report log
2026/03/09 16:06 12m retest repro https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing report log
2026/02/23 12:15 12m retest repro https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing report log
2026/02/23 12:15 13m retest repro https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing report log
2026/02/23 12:15 13m retest repro https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing report log
2026/02/23 12:15 46m retest repro https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing report log
2026/02/23 12:15 40m retest repro https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing report log
2026/02/13 21:30 17m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git da87d45b OK log
2026/02/09 16:34 45m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git da87d45b1951 OK log
2026/02/09 01:26 17m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git da87d45b1951 OK log
2026/02/08 21:33 18m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git da87d45b1951 report log
2026/02/08 20:14 14m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git da87d45b1951 report log
2026/02/08 15:20 17m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git da87d45b1951 report log
2026/02/08 14:47 12m stern@rowland.harvard.edu patch https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git da87d45b1951 report log

Sample crash report:
INFO: task syz.3.17:3964 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.3.17        state:D stack:27128 pid:3964  tgid:3964  ppid:3515   task_flags:0x400040 flags:0x00080002
Call Trace:
 <TASK>
 context_switch kernel/sched/core.c:5260 [inline]
 __schedule+0xeb0/0x3e50 kernel/sched/core.c:6867
 __schedule_loop kernel/sched/core.c:6949 [inline]
 schedule+0xdd/0x390 kernel/sched/core.c:6964
 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99
 do_wait_for_common kernel/sched/completion.c:100 [inline]
 __wait_for_common+0x2e7/0x4c0 kernel/sched/completion.c:121
 usb_start_wait_urb+0x147/0x4c0 drivers/usb/core/message.c:64
 usb_bulk_msg+0x22b/0x580 drivers/usb/core/message.c:388
 send_request_dev_dep_msg_in drivers/usb/class/usbtmc.c:1350 [inline]
 usbtmc_read+0x5f4/0x10b0 drivers/usb/class/usbtmc.c:1409
 vfs_read+0x1e4/0xb30 fs/read_write.c:570
 ksys_read+0x12a/0x250 fs/read_write.c:715
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x570 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1c641aaeb9
RSP: 002b:00007ffcc3ddcc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007f1c64425fa0 RCX: 00007f1c641aaeb9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f1c64218c1f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1c64425fac R14: 00007f1c64425fa0 R15: 00007f1c64425fa0
 </TASK>

Showing all locks held in the system:
6 locks held by kworker/0:0/9:
 #0: ffff88810528b548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc9000009fca8 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
 #2: ffff88810ab08198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #2: ffff88810ab08198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bd/0x4af0 drivers/usb/core/hub.c:5899
 #3: ffff88811dc3f198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #3: ffff88811dc3f198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1006
 #4: ffff888114b7f160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #4: ffff888114b7f160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1006
 #5: ffffffff8a0d7bb0 (minor_rwsem){++++}-{4:4}, at: usb_register_dev+0x11d/0x570 drivers/usb/core/file.c:134
1 lock held by khungtaskd/30:
 #0: ffffffff894da3a0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:331 [inline]
 #0: ffffffff894da3a0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:867 [inline]
 #0: ffffffff894da3a0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x3d/0x184 kernel/locking/lockdep.c:6775
6 locks held by kworker/1:1/38:
 #0: ffff88810528b548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc90000287ca8 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
 #2: ffff88810aba8198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #2: ffff88810aba8198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bd/0x4af0 drivers/usb/core/hub.c:5899
 #3: ffff888120002198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #3: ffff888120002198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1006
 #4: ffff888112736160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #4: ffff888112736160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1006
 #5: ffffffff8a0d7bb0 (minor_rwsem){++++}-{4:4}, at: usb_register_dev+0x11d/0x570 drivers/usb/core/file.c:134
6 locks held by kworker/0:2/1123:
 #0: ffff88810528b548 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc90001e2fca8 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
 #2: ffff88810ab90198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #2: ffff88810ab90198 (&dev->mutex){....}-{4:4}, at: hub_event+0x1bd/0x4af0 drivers/usb/core/hub.c:5899
 #3: ffff88811e8c2198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #3: ffff88811e8c2198 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1006
 #4: ffff88811e8c5160 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #4: ffff88811e8c5160 (&dev->mutex){....}-{4:4}, at: __device_attach+0x7e/0x4d0 drivers/base/dd.c:1006
 #5: ffffffff8a0d7bb0 (minor_rwsem){++++}-{4:4}, at: usb_register_dev+0x11d/0x570 drivers/usb/core/file.c:134
2 locks held by kworker/u8:11/1173:
 #0: ffff888100089148 ((wq_completion)events_unbound#2){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc90001d7fca8 ((work_completion)(&sub_info->work)){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
3 locks held by kworker/1:2/2487:
 #0: ffff888100071948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc900039ffca8 ((work_completion)(&fw_work->work)){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
 #2: ffff88810ab08198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #2: ffff88810ab08198 (&dev->mutex){....}-{4:4}, at: ath9k_hif_usb_firmware_fail drivers/net/wireless/ath/ath9k/hif_usb.c:1161 [inline]
 #2: ffff88810ab08198 (&dev->mutex){....}-{4:4}, at: ath9k_hif_usb_firmware_cb+0x3b2/0x530 drivers/net/wireless/ath/ath9k/hif_usb.c:1294
2 locks held by getty/2929:
 #0: ffff8881127e90a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x24/0x80 drivers/tty/tty_ldisc.c:243
 #1: ffffc900000452f0 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x419/0x1500 drivers/tty/n_tty.c:2211
1 lock held by syz.3.17/3964:
 #0: ffff888117be9cd8 (&data->io_mutex){+.+.}-{4:4}, at: usbtmc_read+0x154/0x10b0 drivers/usb/class/usbtmc.c:1395
2 locks held by syz.4.18/4420:
 #0: ffffffff8a0d7bb0 (minor_rwsem){++++}-{4:4}, at: usb_open+0x23/0x220 drivers/usb/core/file.c:38
 #1: ffff888117be9cd8 (&data->io_mutex){+.+.}-{4:4}, at: usbtmc_open+0x4c8/0x950 drivers/usb/class/usbtmc.c:189
1 lock held by syz.5.19/4875:
 #0: ffffffff8a0d7bb0 (minor_rwsem){++++}-{4:4}, at: usb_open+0x23/0x220 drivers/usb/core/file.c:38
1 lock held by syz.6.20/5331:
 #0: ffffffff8a0d7bb0 (minor_rwsem){++++}-{4:4}, at: usb_open+0x23/0x220 drivers/usb/core/file.c:38
3 locks held by kworker/1:3/5335:
 #0: ffff888100071948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc9000553fca8 ((work_completion)(&fw_work->work)){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
 #2: ffff88810ab90198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #2: ffff88810ab90198 (&dev->mutex){....}-{4:4}, at: ath9k_hif_usb_firmware_fail drivers/net/wireless/ath/ath9k/hif_usb.c:1161 [inline]
 #2: ffff88810ab90198 (&dev->mutex){....}-{4:4}, at: ath9k_hif_usb_firmware_cb+0x3b2/0x530 drivers/net/wireless/ath/ath9k/hif_usb.c:1294
1 lock held by syz.7.21/5788:
 #0: ffffffff8a0d7bb0 (minor_rwsem){++++}-{4:4}, at: usb_open+0x23/0x220 drivers/usb/core/file.c:38
3 locks held by kworker/1:4/5792:
 #0: ffff888100071948 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x11ae/0x1840 kernel/workqueue.c:3232
 #1: ffffc900066a7ca8 ((work_completion)(&fw_work->work)){+.+.}-{0:0}, at: process_one_work+0x927/0x1840 kernel/workqueue.c:3233
 #2: ffff88810aba8198 (&dev->mutex){....}-{4:4}, at: device_lock include/linux/device.h:895 [inline]
 #2: ffff88810aba8198 (&dev->mutex){....}-{4:4}, at: ath9k_hif_usb_firmware_fail drivers/net/wireless/ath/ath9k/hif_usb.c:1161 [inline]
 #2: ffff88810aba8198 (&dev->mutex){....}-{4:4}, at: ath9k_hif_usb_firmware_cb+0x3b2/0x530 drivers/net/wireless/ath/ath9k/hif_usb.c:1294
1 lock held by modprobe/5855:

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

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 30 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x100/0x190 lib/dump_stack.c:120
 nmi_cpu_backtrace.cold+0x12d/0x151 lib/nmi_backtrace.c:113
 nmi_trigger_cpumask_backtrace+0x1d7/0x230 lib/nmi_backtrace.c:62
 trigger_all_cpu_backtrace include/linux/nmi.h:161 [inline]
 __sys_info lib/sys_info.c:157 [inline]
 sys_info+0x141/0x190 lib/sys_info.c:165
 check_hung_uninterruptible_tasks kernel/hung_task.c:346 [inline]
 watchdog+0xcc3/0xfe0 kernel/hung_task.c:515
 kthread+0x3b3/0x730 kernel/kthread.c:463
 ret_from_fork+0x6c3/0xa20 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 5856 Comm: modprobe Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/24/2026
RIP: 0010:mas_next_slot+0x315/0x18b0 lib/maple_tree.c:4378
Code: 44 24 48 4d 8b 3f 48 89 44 24 18 48 8b 44 24 50 49 83 c7 01 80 38 00 0f 85 6e 12 00 00 4d 89 7d 08 e8 af f6 63 fa 48 8b 0c 24 <45> 8d 7e 01 48 be 00 00 00 00 00 fc ff df 48 89 c8 83 e1 07 48 c1
RSP: 0018:ffffc9000691f9f8 EFLAGS: 00000293
RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffc9000691fb85
RDX: ffff88810f3c8000 RSI: ffffffff874d4551 RDI: ffff88810f3c8000
RBP: ffff88810dbf2800 R08: 0000000000000000 R09: 0000000000000003
R10: 000000000000000e R11: 0000000000000000 R12: 000000000000000e
R13: ffffc9000691fb38 R14: 0000000000000003 R15: 00007fbad9e9e000
FS:  00007fbad9c08c80(0000) GS:ffff88826896a000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbad9c9d2fe CR3: 0000000109bdc000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 mas_find+0x2ad/0x740 lib/maple_tree.c:5622
 vma_next include/linux/mm.h:1118 [inline]
 validate_mm+0x11d/0x4e0 mm/vma.c:648
 do_brk_flags+0x914/0xf30 mm/vma.c:2898
 __do_sys_brk+0x66f/0xa40 mm/mmap.c:194
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x570 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbad9dc76c7
Code: 4d 85 ed 74 e0 4d 85 e4 74 0b 48 89 ef 41 ff d4 4c 89 ee eb da 48 89 f7 e8 e6 1c f3 ff eb f1 0f 1f 40 00 b8 0c 00 00 00 0f 05 <48> 8b 15 6a a7 0d 00 48 89 02 48 39 f8 72 0a 31 c0 c3 0f 1f 80 00
RSP: 002b:00007ffc55277358 EFLAGS: 00000206 ORIG_RAX: 000000000000000c
RAX: ffffffffffffffda RBX: 000055a87aa59000 RCX: 00007fbad9dc76c7
RDX: 00007fbad9ea9e50 RSI: 00007fbad9ea2ac0 RDI: 000055a87aa59000
RBP: 000055a87aa38000 R08: 0000000000021000 R09: 0000000000000000
R10: 00007fbad9ea2ac0 R11: 0000000000000206 R12: 00007fbad9ea9e50
R13: 00007fbad9ea2b20 R14: 0000000000001000 R15: 00000000000002b0
 </TASK>

Crashes (8):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/09 09:55 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing da87d45b1951 4c131dc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task hung in usb_bulk_msg
2026/02/09 04:34 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing da87d45b1951 4c131dc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task hung in usb_bulk_msg
2026/02/08 22:53 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing da87d45b1951 4c131dc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task hung in usb_bulk_msg
2026/02/08 17:25 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing da87d45b1951 4c131dc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task hung in usb_bulk_msg
2026/02/08 12:02 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing da87d45b1951 4c131dc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task hung in usb_bulk_msg
2026/02/08 06:39 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing da87d45b1951 4c131dc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task hung in usb_bulk_msg
2026/02/08 01:16 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing da87d45b1951 4c131dc4 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task hung in usb_bulk_msg
2026/02/07 19:53 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing da87d45b1951 4c131dc4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-usb INFO: task hung in usb_bulk_msg
* Struck through repros no longer work on HEAD.