WARNING in device_remove

Status: upstream: reported on 2026/08/14 00:04
Subsystems: kernel
Labels: prio:high
[Documentation on labels]
Reported-by: syzbot+7371a1a749c42016f046@syzkaller.appspotmail.com
First crash: 5d11h, last: 5d11h
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision
d99b5cf5 assessment-security DenialOfService: ✅ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ✅ RemoteTrigger: ❌ Unprivileged: ❌ UserNamespace: ❌ VMGuestTrigger: ❌ VMHostTrigger: ❌ WARNING in device_remove 2026/08/11 01:05 2026/08/11 01:05 2026/08/11 03:56 039457bd
Discussions (1)
Title Replies (including bot) Last reply
[syzbot] [kernel?] WARNING in device_remove 0 (1) 2026/08/14 00:04

Sample crash report:
usb 7-1: USB disconnect, device number 4
------------[ cut here ]------------
!work->func
WARNING: kernel/workqueue.c:4335 at __flush_work+0xa5d/0xcb0 kernel/workqueue.c:4335, CPU#0: kworker/0:6/5370
Modules linked in:
CPU: 0 UID: 0 PID: 5370 Comm: kworker/0:6 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: usb_hub_wq hub_event

RIP: 0010:__flush_work+0xa5d/0xcb0 kernel/workqueue.c:4335
Code: 35 00 00 00 00 e8 13 2c 12 00 e8 6e 8d 1b 00 c6 44 24 0f 00 e9 91 fd ff ff e8 0f 00 36 00 90 0f 0b 90 eb eb e8 04 00 36 00 90 <0f> 0b 90 eb e0 e8 f9 ff 35 00 e8 f4 ff 35 00 48 8b 3c 24 e8 6b b8
RSP: 0018:ffffc90004097228 EFLAGS: 00010287
RAX: 0000000000021e96 RBX: dffffc0000000000 RCX: ffffc90011b77000
RDX: 0000000000100000 RSI: ffffffff817e043c RDI: ffff888118583c00
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88811a5c88f0 R14: 0000000000000001 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff888268636000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c322071 CR3: 000000013af66000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 __cancel_work_sync kernel/workqueue.c:4494 [inline]
 cancel_work_sync+0xd1/0xf0 kernel/workqueue.c:4531
 device_remove+0xcb/0x180 drivers/base/dd.c:616
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
 device_del+0x376/0x9b0 drivers/base/core.c:3961
 hid_remove_device drivers/hid/hid-core.c:3071 [inline]
 hid_destroy_device+0x19c/0x240 drivers/hid/hid-core.c:3093
 usbhid_disconnect+0xa0/0xe0 drivers/hid/usbhid/hid-core.c:1479
 device_remove drivers/base/dd.c:618 [inline]
 device_remove+0x12a/0x180 drivers/base/dd.c:610
 __device_release_driver drivers/base/dd.c:1349 [inline]
 device_release_driver_internal+0x44e/0x620 drivers/base/dd.c:1372
 bus_remove_device+0x2bc/0x560 drivers/base/bus.c:664
 device_del+0x376/0x9b0 drivers/base/core.c:3961
 usb_disable_device+0x367/0x810 drivers/usb/core/message.c:1478
 hub_port_connect drivers/usb/core/hub.c:5412 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5712 [inline]
 port_event drivers/usb/core/hub.c:5876 [inline]
 hub_event+0x1d0c/0x4af0 drivers/usb/core/hub.c:5958
 process_one_work+0xa23/0x1940 kernel/workqueue.c:3322
 process_scheduled_works kernel/workqueue.c:3405 [inline]
 worker_thread+0x5ef/0xe50 kernel/workqueue.c:3486
 kthread+0x370/0x450 kernel/kthread.c:436
 ret_from_fork+0x69a/0xc80 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/09 11:21 https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git usb-testing 5d5fd841c346 5d63f80b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-usb WARNING in device_remove
* Struck through repros no longer work on HEAD.