syzbot
general protection fault in dummy_udc_stop
Status:
upstream: reported on 2026/08/02 00:01
Subsystems:
usb
Labels:
prio:low
[Documentation on labels]
Reported-by: syzbot+366177ceada8026bb3a6@syzkaller.appspotmail.com
First crash: 10d, last: 3h04m
Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 6399 Comm: syz.0.34 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:dummy_udc_stop+0x74/0x120 drivers/usb/gadget/udc/dummy_hcd.c:1053
Code: 8d 1c c3 48 81 c3 90 06 00 00 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 46 e8 7d fa 48 8b 1b 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 2d e8 7d fa 48 8b 1b 48 89 df e8
RSP: 0018:ffffc90003e8f848 EFLAGS: 00010256
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888036079f00 RSI: 0000000000000003 RDI: 0000000000000005
RBP: 0000000000000003 R08: ffffffff90579d37 R09: 1ffffffff20af3a6
R10: dffffc0000000000 R11: ffffffff87b6c2e0 R12: 1ffff110053fb89e
R13: ffffffff8cb15858 R14: dffffc0000000000 R15: ffff888026540c00
FS: 0000000000000000(0000) GS:ffff888124f4b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f48b76e9000 CR3: 00000000560cd000 CR4: 0000000000350ef0
Call Trace:
<TASK>
usb_gadget_udc_stop_locked drivers/usb/gadget/udc/core.c:1265 [inline]
gadget_unbind_driver+0x25f/0x410 drivers/usb/gadget/udc/core.c:1727
device_remove drivers/base/dd.c:616 [inline]
__device_release_driver drivers/base/dd.c:1349 [inline]
device_release_driver_internal+0x48b/0x880 drivers/base/dd.c:1372
driver_detach+0x1f3/0x2d0 drivers/base/dd.c:1435
bus_remove_driver+0x226/0x320 drivers/base/bus.c:832
usb_gadget_unregister_driver+0x4e/0x70 drivers/usb/gadget/udc/core.c:1784
raw_release+0xd7/0x260 drivers/usb/gadget/legacy/raw_gadget.c:463
__fput+0x418/0xa50 fs/file_table.c:512
task_work_run+0x1d9/0x270 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x73a/0x2360 kernel/exit.c:1009
do_group_exit+0x22d/0x2f0 kernel/exit.c:1152
get_signal+0x121b/0x12c0 kernel/signal.c:3046
arch_do_signal_or_restart+0xbb/0x860 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0x104/0x730 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x353/0x580 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7ff2ab39dcab
Code: Unable to access opcode bytes at 0x7ff2ab39dc81.
RSP: 002b:00007ff2ac317f00 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: fffffffffffffffc RBX: 0000000000000003 RCX: 00007ff2ab39dcab
RDX: 00007ff2ac318fd0 RSI: 0000000080085502 RDI: 0000000000000003
RBP: 00007ff2ac318fd0 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000080085502
R13: 0000000800000000 R14: 0000000000000003 R15: 00007ff2ab45386a
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:dummy_udc_stop+0x74/0x120 drivers/usb/gadget/udc/dummy_hcd.c:1053
Code: 8d 1c c3 48 81 c3 90 06 00 00 48 89 d8 48 c1 e8 03 42 80 3c 30 00 74 08 48 89 df e8 46 e8 7d fa 48 8b 1b 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 74 08 48 89 df e8 2d e8 7d fa 48 8b 1b 48 89 df e8
RSP: 0018:ffffc90003e8f848 EFLAGS: 00010256
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: ffff888036079f00 RSI: 0000000000000003 RDI: 0000000000000005
RBP: 0000000000000003 R08: ffffffff90579d37 R09: 1ffffffff20af3a6
R10: dffffc0000000000 R11: ffffffff87b6c2e0 R12: 1ffff110053fb89e
R13: ffffffff8cb15858 R14: dffffc0000000000 R15: ffff888026540c00
FS: 0000000000000000(0000) GS:ffff888124f4b000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558dbc3a78 CR3: 0000000052e3f000 CR4: 0000000000350ef0
----------------
Code disassembly (best guess):
0: 8d 1c c3 lea (%rbx,%rax,8),%ebx
3: 48 81 c3 90 06 00 00 add $0x690,%rbx
a: 48 89 d8 mov %rbx,%rax
d: 48 c1 e8 03 shr $0x3,%rax
11: 42 80 3c 30 00 cmpb $0x0,(%rax,%r14,1)
16: 74 08 je 0x20
18: 48 89 df mov %rbx,%rdi
1b: e8 46 e8 7d fa call 0xfa7de866
20: 48 8b 1b mov (%rbx),%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 2d e8 7d fa call 0xfa7de866
39: 48 8b 1b mov (%rbx),%rbx
3c: 48 89 df mov %rbx,%rdi
3f: e8 .byte 0xe8
Struck through repros no longer work on HEAD.