syzbot
general protection fault in set_link_state
Status:
upstream: reported C repro on 2026/07/25 01:05
Reported-by: syzbot+894861fbdf6a7acbaf3e@syzkaller.appspotmail.com
First crash: 17d, last: 2h20m
Sample crash report:
dummy_hcd dummy_hcd.0: remove, state 1
usb usb1: USB disconnect, device number 1
usb 1-1: USB disconnect, device number 2
dummy_hcd dummy_hcd.0: stopped
dummy_hcd dummy_hcd.0: USB bus 1 deregistered
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 5932 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:set_link_state+0x27/0x1000 drivers/usb/gadget/udc/dummy_hcd.c:454
Code: 0f 1f 00 55 41 57 41 56 41 55 41 54 53 48 83 ec 38 49 89 fe 48 bb 00 00 00 00 00 fc ff df e8 80 04 cd fa 4c 89 f0 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 f7 e8 db 86 25 fb 49 8b 0e 4d 8d a6 93 00
RSP: 0018:ffffc900031cfb18 EFLAGS: 00010046
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff8880245a1e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000639f4c R12: 0000000000000a06
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000555568892500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562357004150 CR3: 0000000075bca000 CR4: 00000000003506f0
Call Trace:
<TASK>
dummy_pullup+0xc1/0x120 drivers/usb/gadget/udc/dummy_hcd.c:932
usb_gadget_disconnect_locked+0x120/0x440 drivers/usb/gadget/udc/core.c:782
gadget_unbind_driver+0xc2/0x3e0 drivers/usb/gadget/udc/core.c:1696
device_remove drivers/base/dd.c:626 [inline]
__device_release_driver drivers/base/dd.c:1351 [inline]
device_release_driver_internal+0x408/0x6f0 drivers/base/dd.c:1374
driver_detach+0x1f3/0x2d0 drivers/base/dd.c:1437
bus_remove_driver+0x221/0x2f0 drivers/base/bus.c:792
usb_gadget_unregister_driver+0x4e/0x70 drivers/usb/gadget/udc/core.c:1762
raw_release+0xda/0x260 drivers/usb/gadget/legacy/raw_gadget.c:416
__fput+0x221/0x940 fs/file_table.c:418
task_work_run+0x1d4/0x260 kernel/task_work.c:245
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
exit_to_user_mode_loop+0xe6/0x110 kernel/entry/common.c:177
exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:210
__syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
syscall_exit_to_user_mode+0x1a/0x50 kernel/entry/common.c:302
do_syscall_64+0x61/0xb0 arch/x86/entry/common.c:82
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7ff9b719e0d9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffedeb75628 EFLAGS: 00000246 ORIG_RAX: 00000000000001b4
RAX: 0000000000000000 RBX: 00007ffedeb75710 RCX: 00007ff9b719e0d9
RDX: 0000000000000000 RSI: 000000000000001e RDI: 0000000000000003
RBP: 000000000001bf49 R08: 0000000000000001 R09: 0000000000000000
R10: 0000001b2c420000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff9b7425fac R14: 00007ff9b7425fa8 R15: 00007ff9b7425fa0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:set_link_state+0x27/0x1000 drivers/usb/gadget/udc/dummy_hcd.c:454
Code: 0f 1f 00 55 41 57 41 56 41 55 41 54 53 48 83 ec 38 49 89 fe 48 bb 00 00 00 00 00 fc ff df e8 80 04 cd fa 4c 89 f0 48 c1 e8 03 <80> 3c 18 00 74 08 4c 89 f7 e8 db 86 25 fb 49 8b 0e 4d 8d a6 93 00
RSP: 0018:ffffc900031cfb18 EFLAGS: 00010046
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff8880245a1e00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000639f4c R12: 0000000000000a06
R13: dffffc0000000000 R14: 0000000000000000 R15: 0000000000000000
FS: 0000555568892500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000562357004150 CR3: 0000000075bca000 CR4: 00000000003506f0
----------------
Code disassembly (best guess):
0: 0f 1f 00 nopl (%rax)
3: 55 push %rbp
4: 41 57 push %r15
6: 41 56 push %r14
8: 41 55 push %r13
a: 41 54 push %r12
c: 53 push %rbx
d: 48 83 ec 38 sub $0x38,%rsp
11: 49 89 fe mov %rdi,%r14
14: 48 bb 00 00 00 00 00 movabs $0xdffffc0000000000,%rbx
1b: fc ff df
1e: e8 80 04 cd fa call 0xfacd04a3
23: 4c 89 f0 mov %r14,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1) <-- trapping instruction
2e: 74 08 je 0x38
30: 4c 89 f7 mov %r14,%rdi
33: e8 db 86 25 fb call 0xfb258713
38: 49 8b 0e mov (%r14),%rcx
3b: 4d rex.WRB
3c: 8d .byte 0x8d
3d: a6 cmpsb %es:(%rdi),%ds:(%rsi)
3e: 93 xchg %eax,%ebx
Struck through repros no longer work on HEAD.