WARNING in usb_ep_enable

Status: upstream: reported C repro on 2026/08/01 09:05
Reported-by: syzbot+b97587abb3b094010b9b@syzkaller.appspotmail.com
First crash: 4d16h, last: 3d11h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING in usb_ep_enable origin:upstream -1 syz, C 31 4d00h 5d05h 0/3 upstream: reported C repro on 2026/07/31 20:18
android-6-12 WARNING in usb_ep_enable -1 syz, C 13 5h57m 6d11h 0/1 premoderation: reported C repro on 2026/07/30 13:40
upstream WARNING in usb_ep_enable usb prio:high -1 syz, C done 126 16m 5d08h 0/29 upstream: reported C repro on 2026/07/31 17:13
linux-6.6 WARNING in usb_ep_enable -1 syz, C 15 1d06h 5d04h 0/2 upstream: reported C repro on 2026/07/31 21:09

Sample crash report:
------------[ cut here ]------------
usb_ep_enable: ep129 (ep1in-bulk) has maxpacket 0
WARNING: CPU: 0 PID: 14 at drivers/usb/gadget/udc/core.c:125 usb_ep_enable+0x27c/0x4d0 drivers/usb/gadget/udc/core.c:124
Modules linked in:
CPU: 0 PID: 14 Comm: kworker/0:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:usb_ep_enable+0x27c/0x4d0 drivers/usb/gadget/udc/core.c:124
Code: 49 8b 0e 48 c7 c0 80 cf 3e 8b 49 c7 c0 a0 cf 3e 8b 4c 0f 44 c0 48 c7 c7 40 cf 3e 8b 48 c7 c6 19 aa 63 8c 89 ea e8 d4 f4 ce fa <0f> 0b e9 c4 fe ff ff e8 78 6a 03 fb 49 bc 00 00 00 00 00 fc ff df
RSP: 0018:ffffc90000007788 EFLAGS: 00010046
RAX: 8770641b6d04a100 RBX: ffff8881463d00e0 RCX: ffff88813fea1e00
RDX: 0000000000000100 RSI: 0000000000000000 RDI: 0000000000000002
RBP: 0000000000000081 R08: ffff8880b8e279db R09: 1ffff110171c4f3b
R10: dffffc0000000000 R11: ffffed10171c4f3c R12: dffffc0000000000
R13: ffff8881463d010d R14: ffff8881463d00e8 R15: ffff88802ec5efba
FS:  0000000000000000(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000033f6242bc000 CR3: 00000000799d6000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <IRQ>
 hidg_set_alt+0x126/0xa00 drivers/usb/gadget/function/f_hid.c:822
 set_config+0x6e8/0xf70 drivers/usb/gadget/composite.c:986
 composite_setup+0x194c/0x2b00 drivers/usb/gadget/composite.c:1893
 configfs_composite_setup+0xc3/0x100 drivers/usb/gadget/configfs.c:1484
 dummy_timer+0x12ea/0x3420 drivers/usb/gadget/udc/dummy_hcd.c:1936
 __run_hrtimer kernel/time/hrtimer.c:1751 [inline]
 __hrtimer_run_queues+0x522/0xc90 kernel/time/hrtimer.c:1815
 hrtimer_run_softirq+0x173/0x290 kernel/time/hrtimer.c:1832
 handle_softirqs+0x291/0x910 kernel/softirq.c:596
 __do_softirq kernel/softirq.c:630 [inline]
 invoke_softirq kernel/softirq.c:470 [inline]
 __irq_exit_rcu+0x13b/0x230 kernel/softirq.c:679
 irq_exit_rcu+0x5/0x20 kernel/softirq.c:691
 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1118 [inline]
 sysvec_apic_timer_interrupt+0xa0/0xc0 arch/x86/kernel/apic/apic.c:1118
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x16/0x20 arch/x86/include/asm/idtentry.h:691
RIP: 0010:__raw_spin_unlock_irqrestore include/linux/spinlock_api_smp.h:152 [inline]
RIP: 0010:_raw_spin_unlock_irqrestore+0xbc/0x120 kernel/locking/spinlock.c:194
Code: c7 44 24 20 00 00 00 00 9c 8f 44 24 20 f7 44 24 20 00 02 00 00 41 c6 04 07 f8 75 4b f7 c3 00 02 00 00 74 01 fb bf 01 00 00 00 <e8> 3f 89 1e f7 65 8b 05 b0 3a c8 75 85 c0 74 3c 48 c7 04 24 0e 36
RSP: 0018:ffffc90000137080 EFLAGS: 00000206
RAX: dffffc0000000004 RBX: 0000000000000a02 RCX: 8770641b6d04a100
RDX: dffffc0000000000 RSI: ffffffff8a8c17a0 RDI: 0000000000000001
RBP: ffffc90000137100 R08: ffffffff90b102af R09: 1ffffffff2162055
R10: dffffc0000000000 R11: fffffbfff2162056 R12: dffffc0000000000
R13: dffffc0000000000 R14: ffff8881463d0000 R15: 1ffff92000026e10
 spin_unlock_irqrestore include/linux/spinlock.h:406 [inline]
 dummy_urb_enqueue+0x583/0x770 drivers/usb/gadget/udc/dummy_hcd.c:1319
 usb_hcd_submit_urb+0x314/0x1970 drivers/usb/core/hcd.c:1558
 usb_start_wait_urb+0x13c/0x580 drivers/usb/core/message.c:61
 usb_internal_control_msg drivers/usb/core/message.c:116 [inline]
 usb_control_msg+0x231/0x3e0 drivers/usb/core/message.c:166
 usb_control_msg_send drivers/usb/core/message.c:225 [inline]
 usb_set_configuration+0x11a7/0x2030 drivers/usb/core/message.c:2164
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x126/0x250 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x24a/0xb40 drivers/base/dd.c:638
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:804
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:834
 __device_attach_driver+0x2c6/0x510 drivers/base/dd.c:962
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a7/0x480 drivers/base/dd.c:1034
 bus_probe_device+0xba/0x1d0 drivers/base/bus.c:489
 device_add+0xbcf/0x1050 drivers/base/core.c:3712
 usb_new_device+0xa01/0x15e0 drivers/usb/core/hub.c:2659
 hub_port_connect drivers/usb/core/hub.c:5517 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5657 [inline]
 port_event drivers/usb/core/hub.c:5817 [inline]
 hub_event+0x2b2f/0x5200 drivers/usb/core/hub.c:5899
 process_one_work+0x8ab/0x1160 kernel/workqueue.c:2292
 worker_thread+0xaf5/0x12a0 kernel/workqueue.c:2439
 kthread+0x29d/0x330 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295
 </TASK>
----------------
Code disassembly (best guess):
   0:	c7 44 24 20 00 00 00 	movl   $0x0,0x20(%rsp)
   7:	00
   8:	9c                   	pushf
   9:	8f 44 24 20          	pop    0x20(%rsp)
   d:	f7 44 24 20 00 02 00 	testl  $0x200,0x20(%rsp)
  14:	00
  15:	41 c6 04 07 f8       	movb   $0xf8,(%r15,%rax,1)
  1a:	75 4b                	jne    0x67
  1c:	f7 c3 00 02 00 00    	test   $0x200,%ebx
  22:	74 01                	je     0x25
  24:	fb                   	sti
  25:	bf 01 00 00 00       	mov    $0x1,%edi
* 2a:	e8 3f 89 1e f7       	call   0xf71e896e <-- trapping instruction
  2f:	65 8b 05 b0 3a c8 75 	mov    %gs:0x75c83ab0(%rip),%eax        # 0x75c83ae6
  36:	85 c0                	test   %eax,%eax
  38:	74 3c                	je     0x76
  3a:	48                   	rex.W
  3b:	c7                   	.byte 0xc7
  3c:	04 24                	add    $0x24,%al
  3e:	0e                   	(bad)
  3f:	36                   	ss

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/02 13:34 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/02 11:47 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/02 11:44 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/02 11:41 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/02 11:41 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/01 12:03 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/01 12:02 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/01 12:02 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/01 12:02 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in usb_ep_enable
2026/08/01 09:04 linux-6.1.y fb28aa725e05 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in usb_ep_enable
* Struck through repros no longer work on HEAD.