general protection fault in dummy_udc_stop

Status: premoderation: reported on 2026/08/02 20:29
Reported-by: syzbot+a3bb5c815dcbd454875f@syzkaller.appspotmail.com
First crash: 3d08h, last: 3d08h
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-5-15 general protection fault in dummy_udc_stop 2 2 1d03h 6d17h 0/2 premoderation: reported on 2026/07/30 11:35
android-5-10 general protection fault in dummy_udc_stop 2 1 11d 11d 0/2 premoderation: reported on 2026/07/25 11:23
android-6-12 general protection fault in dummy_udc_stop 2 2 4d00h 10d 0/1 premoderation: reported on 2026/07/26 08:20
upstream general protection fault in dummy_udc_stop usb prio:low 8 7 1d10h 4d05h 0/29 upstream: reported on 2026/08/02 00:01

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 PID: 10370 Comm: syz.0.3158 Tainted: G        W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:dummy_udc_stop+0x7e/0x330 drivers/usb/gadget/udc/dummy_hcd.c:1034
Code: 4d 8d bc c7 e0 04 00 00 4c 89 f8 48 c1 e8 03 80 3c 18 00 49 89 de 74 08 4c 89 ff e8 1c 8b 6a fe 49 8b 1f 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 03 8b 6a fe 48 8b 1b 48 89 df e8
RSP: 0018:ffffc900009f7608 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8881204e2880 RSI: 0000000000000003 RDI: 0000000000000005
RBP: ffffc900009f7660 R08: ffffc900009f75e7 R09: 1ffff9200013eebc
R10: 0000000000000000 R11: ffffffff834c6560 R12: ffff88810d87cc90
R13: ffffffff85e37148 R14: dffffc0000000000 R15: ffff88810d87d170
FS:  0000000000000000(0000) GS:ffff8881f6f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c24a549 CR3: 000000013becb000 CR4: 00000000003506a0
Call Trace:
 <TASK>
 usb_gadget_udc_stop_locked drivers/usb/gadget/udc/core.c:1254 [inline]
 gadget_unbind_driver+0x28c/0x3d0 drivers/usb/gadget/udc/core.c:1688
 device_remove drivers/base/dd.c:548 [inline]
 __device_release_driver drivers/base/dd.c:1283 [inline]
 device_release_driver_internal+0x486/0x7e0 drivers/base/dd.c:1309
 driver_detach+0x1f1/0x2d0 drivers/base/dd.c:1372
 bus_remove_driver+0x121/0x1d0 drivers/base/bus.c:679
 driver_unregister+0x75/0xa0 drivers/base/driver.c:274
 usb_gadget_unregister_driver+0x4e/0x70 drivers/usb/gadget/udc/core.c:1745
 raw_release+0xda/0x260 drivers/usb/gadget/legacy/raw_gadget.c:416
 __fput+0x1fd/0x8f0 fs/file_table.c:320
 ____fput+0x15/0x20 fs/file_table.c:348
 task_work_run+0x1e1/0x250 kernel/task_work.c:203
 exit_task_work include/linux/task_work.h:39 [inline]
 do_exit+0xaf2/0x2850 kernel/exit.c:887
 do_group_exit+0x21b/0x2e0 kernel/exit.c:1030
 get_signal+0x167c/0x1700 kernel/signal.c:2895
 arch_do_signal_or_restart+0xd1/0x11c0 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f965639dcab
Code: Unable to access opcode bytes at 0x7f965639dc81.
RSP: 002b:00007f9657289f00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00007f965639dcab
RDX: 00007f965728afd0 RSI: 0000000080085502 RDI: 0000000000000003
RBP: 00007f965728afd0 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000080085502
R13: 0000000800000000 R14: 0000000000000003 R15: 00007f965645386a
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dummy_udc_stop+0x7e/0x330 drivers/usb/gadget/udc/dummy_hcd.c:1034
Code: 4d 8d bc c7 e0 04 00 00 4c 89 f8 48 c1 e8 03 80 3c 18 00 49 89 de 74 08 4c 89 ff e8 1c 8b 6a fe 49 8b 1f 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 03 8b 6a fe 48 8b 1b 48 89 df e8
RSP: 0018:ffffc900009f7608 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff8881204e2880 RSI: 0000000000000003 RDI: 0000000000000005
RBP: ffffc900009f7660 R08: ffffc900009f75e7 R09: 1ffff9200013eebc
R10: 0000000000000000 R11: ffffffff834c6560 R12: ffff88810d87cc90
R13: ffffffff85e37148 R14: dffffc0000000000 R15: ffff88810d87d170
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f23edfef2f8 CR3: 000000012d991000 CR4: 00000000003506b0
----------------
Code disassembly (best guess):
   0:	4d 8d bc c7 e0 04 00 	lea    0x4e0(%r15,%rax,8),%r15
   7:	00
   8:	4c 89 f8             	mov    %r15,%rax
   b:	48 c1 e8 03          	shr    $0x3,%rax
   f:	80 3c 18 00          	cmpb   $0x0,(%rax,%rbx,1)
  13:	49 89 de             	mov    %rbx,%r14
  16:	74 08                	je     0x20
  18:	4c 89 ff             	mov    %r15,%rdi
  1b:	e8 1c 8b 6a fe       	call   0xfe6a8b3c
  20:	49 8b 1f             	mov    (%r15),%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 03 8b 6a fe       	call   0xfe6a8b3c
  39:	48 8b 1b             	mov    (%rbx),%rbx
  3c:	48 89 df             	mov    %rbx,%rdi
  3f:	e8                   	.byte 0xe8

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/02 20:28 android14-6.1 92668decd5e0 e611ffe1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-6-1 general protection fault in dummy_udc_stop
* Struck through repros no longer work on HEAD.