general protection fault in dummy_udc_start

Status: upstream: reported C repro on 2026/07/25 16:07
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+56fc9c9b8bc143711dc6@syzkaller.appspotmail.com
First crash: 6d04h, last: 22h26m
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/07/31 upstream (ToT) 8ba098e6b6ff C [report] general protection fault in set_link_state
▶ ▼ Similar bugs (7)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-6.1 BUG: unable to handle kernel paging request in dummy_udc_start 8 syz, C 103 1h42m 6d22h 0/3 upstream: reported C repro on 2026/07/24 22:21
android-6-1 general protection fault in dummy_udc_start 2 syz 116 1d01h 7d02h 0/2 premoderation: reported syz repro on 2026/07/24 17:41
upstream general protection fault in dummy_udc_start usb prio:low 10 syz, C 1389 now 3d06h 0/29 upstream: reported C repro on 2026/07/28 14:15
android-5-15 general protection fault in dummy_udc_start 2 syz 215 12h18m 6d14h 0/2 premoderation: reported syz repro on 2026/07/25 06:03
android-6-12 general protection fault in dummy_udc_start 2 syz 181 3h24m 7d05h 0/1 premoderation: reported syz repro on 2026/07/24 15:05
android-5-10 general protection fault in dummy_udc_start 2 syz, C 239 1d12h 2d06h 0/2 upstream: reported C repro on 2026/07/29 14:38
linux-6.6 general protection fault in dummy_udc_start 2 28 13h33m 6d03h 0/2 upstream: reported on 2026/07/25 17:39

Sample crash report:
dummy_hcd dummy_hcd.0: remove, state 4
usb usb1: USB disconnect, device number 1
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: 1 PID: 4322 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:dummy_udc_start+0xb7/0x1d0 drivers/usb/gadget/udc/dummy_hcd.c:1000
Code: 00 00 ff 24 c5 c0 3f d5 8a e8 f5 8e 42 fb eb 13 e8 ee 8e 42 fb eb 0c e8 e7 8e 42 fb eb 05 e8 e0 8e 42 fb 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 8a b1 87 fb 4d 8b 36 4c 89 f7 e8
RSP: 0018:ffffc9000302fb20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88807d0bc050 RCX: ffff88802118bb80
RDX: 0000000000000000 RSI: ffffffff8ced7b00 RDI: 0000000000000002
RBP: ffffffff863671f0 R08: ffff88802118bb80 R09: 0000000000000004
R10: 0000000000000005 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000002
FS:  0000555572264500(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f65282a4000 CR3: 0000000075105000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 usb_gadget_udc_start drivers/usb/gadget/udc/core.c:1150 [inline]
 udc_bind_to_driver+0x2b5/0x5f0 drivers/usb/gadget/udc/core.c:1577
 usb_gadget_probe_driver+0x1fb/0x380 drivers/usb/gadget/udc/core.c:1637
 raw_ioctl_run drivers/usb/gadget/legacy/raw_gadget.c:549 [inline]
 raw_ioctl+0x115e/0x3750 drivers/usb/gadget/legacy/raw_gadget.c:1256
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f65282bab2b
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007ffdf79d0d10 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007f65282bab2b
RDX: 0000000000000000 RSI: 0000000000005501 RDI: 0000000000000004
RBP: 00007ffdf79d1de0 R08: 0000000000000001 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000200000000080 R14: 0000000000000002 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 42b2116a7bf57ec6 ]---
RIP: 0010:dummy_udc_start+0xb7/0x1d0 drivers/usb/gadget/udc/dummy_hcd.c:1000
Code: 00 00 ff 24 c5 c0 3f d5 8a e8 f5 8e 42 fb eb 13 e8 ee 8e 42 fb eb 0c e8 e7 8e 42 fb eb 05 e8 e0 8e 42 fb 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 8a b1 87 fb 4d 8b 36 4c 89 f7 e8
RSP: 0018:ffffc9000302fb20 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88807d0bc050 RCX: ffff88802118bb80
RDX: 0000000000000000 RSI: ffffffff8ced7b00 RDI: 0000000000000002
RBP: ffffffff863671f0 R08: ffff88802118bb80 R09: 0000000000000004
R10: 0000000000000005 R11: 0000000000000000 R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000002
FS:  0000555572264500(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f65282a4000 CR3: 0000000075105000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	00 00                	add    %al,(%rax)
   2:	ff 24 c5 c0 3f d5 8a 	jmp    *-0x752ac040(,%rax,8)
   9:	e8 f5 8e 42 fb       	call   0xfb428f03
   e:	eb 13                	jmp    0x23
  10:	e8 ee 8e 42 fb       	call   0xfb428f03
  15:	eb 0c                	jmp    0x23
  17:	e8 e7 8e 42 fb       	call   0xfb428f03
  1c:	eb 05                	jmp    0x23
  1e:	e8 e0 8e 42 fb       	call   0xfb428f03
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 20 00       	cmpb   $0x0,(%rax,%r12,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 f7             	mov    %r14,%rdi
  34:	e8 8a b1 87 fb       	call   0xfb87b1c3
  39:	4d 8b 36             	mov    (%r14),%r14
  3c:	4c 89 f7             	mov    %r14,%rdi
  3f:	e8                   	.byte 0xe8

Crashes (26):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/25 17:16 linux-5.15.y 674f684f7c61 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/30 22:14 linux-5.15.y 6e2fd6534337 aaffb173 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/29 22:10 linux-5.15.y 674f684f7c61 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/29 22:08 linux-5.15.y 674f684f7c61 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/29 22:08 linux-5.15.y 674f684f7c61 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/29 22:08 linux-5.15.y 674f684f7c61 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/29 17:12 linux-5.15.y 674f684f7c61 6ef5c1e2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/29 05:26 linux-5.15.y 674f684f7c61 19622d9d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/28 23:27 linux-5.15.y 674f684f7c61 edc8a875 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/28 23:27 linux-5.15.y 674f684f7c61 edc8a875 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/28 08:10 linux-5.15.y 674f684f7c61 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/28 08:10 linux-5.15.y 674f684f7c61 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/27 03:41 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/27 03:30 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 12:11 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 12:03 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 12:00 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 12:00 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 10:16 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 10:15 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 10:12 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 10:11 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/26 04:16 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/25 19:42 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/25 19:35 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
2026/07/25 16:06 linux-5.15.y 674f684f7c61 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in dummy_udc_start
* Struck through repros no longer work on HEAD.