syzbot

usb 2-1: SerialNumber: syz
usb 2-1: config 0 descriptor??
usb 2-1: USB disconnect, device number 2
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WARNING: CPU: 0 PID: 10 at lib/refcount.c:28 refcount_warn_saturate+0x13c/0x174 lib/refcount.c:28
refcount_t: underflow; use-after-free.
Modules linked in:
Kernel panic - not syncing: kernel: panic_on_warn set ...
CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Not tainted syzkaller #0 PREEMPT 
Hardware name: ARM-Versatile Express
Workqueue: usb_hub_wq hub_event
Call trace: 
[<80201a24>] (dump_backtrace) from [<80201b20>] (show_stack+0x18/0x1c arch/arm/kernel/traps.c:257)
 r7:82252114 r6:8320ec00 r5:00000000 r4:82263df8
[<80201b08>] (show_stack) from [<8021f8f0>] (__dump_stack lib/dump_stack.c:94 [inline])
[<80201b08>] (show_stack) from [<8021f8f0>] (dump_stack_lvl+0x54/0x7c lib/dump_stack.c:120)
[<8021f89c>] (dump_stack_lvl) from [<8021f930>] (dump_stack+0x18/0x1c lib/dump_stack.c:129)
 r5:00000000 r4:82a78d18
[<8021f918>] (dump_stack) from [<802025f8>] (vpanic+0xe0/0x2e8 kernel/panic.c:489)
[<80202518>] (vpanic) from [<80202834>] (trace_suspend_resume+0x0/0xd8 kernel/panic.c:626)
 r7:808ce370
[<80202800>] (panic) from [<80252948>] (check_panic_on_warn kernel/panic.c:376 [inline])
[<80202800>] (panic) from [<80252948>] (get_taint+0x0/0x1c kernel/panic.c:371)
 r3:8280c684 r2:00000001 r1:8224a668 r0:82252114
[<802528d0>] (check_panic_on_warn) from [<80252aac>] (__warn+0x80/0x188 kernel/panic.c:897)
[<80252a2c>] (__warn) from [<80252d9c>] (warn_slowpath_fmt+0x1e8/0x1f4 kernel/panic.c:932)
 r8:00000009 r7:822bcd88 r6:df841bfc r5:8320ec00 r4:00000000
[<80252bb8>] (warn_slowpath_fmt) from [<808ce370>] (refcount_warn_saturate+0x13c/0x174 lib/refcount.c:28)
 r10:00000100 r9:829d7a7c r8:84b0ec88 r7:84b0fc74 r6:856e87b4 r5:84b0fc00
 r4:84eda200
[<808ce234>] (refcount_warn_saturate) from [<81a1cec8>] (__refcount_sub_and_test include/linux/refcount.h:400 [inline])
[<808ce234>] (refcount_warn_saturate) from [<81a1cec8>] (__refcount_dec_and_test include/linux/refcount.h:432 [inline])
[<808ce234>] (refcount_warn_saturate) from [<81a1cec8>] (refcount_dec_and_test include/linux/refcount.h:450 [inline])
[<808ce234>] (refcount_warn_saturate) from [<81a1cec8>] (kref_put include/linux/kref.h:64 [inline])
[<808ce234>] (refcount_warn_saturate) from [<81a1cec8>] (kobject_put+0x158/0x1f4 lib/kobject.c:737)
[<81a1cd70>] (kobject_put) from [<80b557c8>] (put_device+0x18/0x1c drivers/base/core.c:3797)
 r7:84b0fc74 r6:856e87b4 r5:84b0fc00 r4:856e8000
[<80b557b0>] (put_device) from [<814584a4>] (hdm_disconnect+0x90/0x9c drivers/most/most_usb.c:1129)
[<81458414>] (hdm_disconnect) from [<80eb6990>] (usb_unbind_interface+0x84/0x2b8 drivers/usb/core/driver.c:458)
 r7:84b0fc74 r6:84b0fc30 r5:00000000 r4:84b0ec00
[<80eb690c>] (usb_unbind_interface) from [<80b5d950>] (device_remove drivers/base/dd.c:571 [inline])
[<80eb690c>] (usb_unbind_interface) from [<80b5d950>] (device_remove+0x64/0x6c drivers/base/dd.c:563)
 r10:00000100 r9:84b0ec88 r8:00000044 r7:84b0fc74 r6:829d7a7c r5:00000000
 r4:84b0fc30
[<80b5d8ec>] (device_remove) from [<80b5ee40>] (__device_release_driver drivers/base/dd.c:1274 [inline])
[<80b5d8ec>] (device_remove) from [<80b5ee40>] (device_release_driver_internal+0x18c/0x200 drivers/base/dd.c:1297)
 r5:00000000 r4:84b0fc30
[<80b5ecb4>] (device_release_driver_internal) from [<80b5eecc>] (device_release_driver+0x18/0x1c drivers/base/dd.c:1320)
 r9:84b0ec88 r8:8335ce40 r7:8335ce38 r6:8335ce0c r5:84b0fc30 r4:8335ce30
[<80b5eeb4>] (device_release_driver) from [<80b5cf90>] (bus_remove_device+0xcc/0x120 drivers/base/bus.c:579)
[<80b5cec4>] (bus_remove_device) from [<80b5721c>] (device_del+0x148/0x38c drivers/base/core.c:3878)
 r9:84b0ec88 r8:8320ec00 r7:04208060 r6:00000000 r5:84b0fc30 r4:84b0fc74
[<80b570d4>] (device_del) from [<80eb427c>] (usb_disable_device+0xd4/0x1e8 drivers/usb/core/message.c:1418)
 r10:00000100 r9:00000000 r8:00000000 r7:84b0fc00 r6:84b0ec00 r5:854a1608
 r4:60000013
[<80eb41a8>] (usb_disable_device) from [<80ea8fec>] (usb_disconnect+0xec/0x2ac drivers/usb/core/hub.c:2344)
 r9:84edbe00 r8:84b0eccc r7:84195400 r6:84b0ec88 r5:84b0ec00 r4:60000013
[<80ea8f00>] (usb_disconnect) from [<80eabfe8>] (hub_port_connect drivers/usb/core/hub.c:5406 [inline])
[<80ea8f00>] (usb_disconnect) from [<80eabfe8>] (hub_port_connect_change drivers/usb/core/hub.c:5706 [inline])
[<80ea8f00>] (usb_disconnect) from [<80eabfe8>] (port_event drivers/usb/core/hub.c:5870 [inline])
[<80ea8f00>] (usb_disconnect) from [<80eabfe8>] (hub_event+0x1194/0x1950 drivers/usb/core/hub.c:5952)
 r10:00000100 r9:83f33f2c r8:84194c00 r7:84b0ec00 r6:83f33800 r5:00000001
 r4:00000001
[<80eaae54>] (hub_event) from [<80278594>] (process_one_work+0x1b4/0x4f4 kernel/workqueue.c:3263)
 r10:83361070 r9:83272c05 r8:8320ec00 r7:dddcfd80 r6:83272c00 r5:83f33f2c
 r4:830b9480
[<802783e0>] (process_one_work) from [<802791dc>] (process_scheduled_works kernel/workqueue.c:3346 [inline])
[<802783e0>] (process_one_work) from [<802791dc>] (worker_thread+0x1fc/0x3d8 kernel/workqueue.c:3427)
 r10:61c88647 r9:8320ec00 r8:830b94ac r7:82804d40 r6:dddcfd80 r5:dddcfda0
 r4:830b9480
[<80278fe0>] (worker_thread) from [<80280200>] (kthread+0x12c/0x280 kernel/kthread.c:463)
 r10:00000000 r9:830b9480 r8:80278fe0 r7:df83de60 r6:830b9580 r5:8320ec00
 r4:00000001
[<802800d4>] (kthread) from [<80200114>] (ret_from_fork+0x14/0x20 arch/arm/kernel/entry-common.S:137)
Exception stack(0xdf841fb0 to 0xdf841ff8)
1fa0:                                     00000000 00000000 00000000 00000000
1fc0: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
1fe0: 00000000 00000000 00000000 00000000 00000013 00000000
 r10:00000000 r9:00000000 r8:00000000 r7:00000000 r6:00000000 r5:802800d4
 r4:830b6340
Rebooting in 86400 seconds..