BUG: unable to handle kernel paging request in dummy_udc_start

Status: upstream: reported C repro on 2026/07/24 22:21
Reported-by: syzbot+b402235664a10e0b8b02@syzkaller.appspotmail.com
First crash: 3d08h, last: 2h25m
▶ ▼ Similar bugs (6)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 general protection fault in dummy_udc_start 2 syz 69 17h34m 3d12h 0/2 premoderation: reported syz repro on 2026/07/24 17:41
android-5-15 general protection fault in dummy_udc_start 2 syz 120 now 3d00h 0/2 premoderation: reported syz repro on 2026/07/25 06:03
android-6-12 general protection fault in dummy_udc_start 2 76 6m 3d15h 0/1 premoderation: reported on 2026/07/24 15:05
android-5-10 general protection fault in dummy_udc_start 2 193 5h28m 3d15h 0/2 premoderation: reported on 2026/07/24 15:20
linux-6.6 general protection fault in dummy_udc_start 2 11 47m 2d12h 0/2 upstream: reported on 2026/07/25 17:39
linux-5.15 general protection fault in dummy_udc_start 2 C 15 1d02h 2d14h 0/3 upstream: reported C repro on 2026/07/25 16:07

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
Unable to handle kernel paging request at virtual address dfff800000000000
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
Mem abort info:
  ESR = 0x0000000096000006
  EC = 0x25: DABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
Data abort info:
  ISV = 0, ISS = 0x00000006
  CM = 0, WnR = 0
[dfff800000000000] address between user and kernel address ranges
Internal error: Oops: 0000000096000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 4513 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/02/2026
pstate: 82400005 (Nzcv daif +PAN -UAO +TCO -DIT -SSBS BTYPE=--)
pc : dummy_udc_start+0xdc/0x1dc drivers/usb/gadget/udc/dummy_hcd.c:1003
lr : dummy_udc_start+0xd8/0x1dc drivers/usb/gadget/udc/dummy_hcd.c:1005
sp : ffff800021157660
x29: ffff800021157660 x28: 1fffe0001a38f401 x27: 1fffe0001a38f400
x26: 1fffe0001ad7b426 x25: dfff800000000000 x24: 1fffe0001a38f496
x23: ffff80000dcebb10 x22: dfff800000000000 x21: 0000000000000003
x20: 0000000000000000 x19: ffff0000d6bda050 x18: 0000000000000000
x17: ffff80000de775d8 x16: ffff800011b90540 x15: 0000000000000000
x14: 0000000000000005 x13: 0000000000ff0100 x12: ffff800016f205f0
x11: ff0080000dcebbe8 x10: 0000000000000000 x9 : ffff80000dcebbe8
x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff8000082d44b0
x2 : ffff0000d4708000 x1 : ffff800016f205c0 x0 : 0000000000000003
Call trace:
 dummy_udc_start+0xdc/0x1dc drivers/usb/gadget/udc/dummy_hcd.c:1003
 usb_gadget_udc_start_locked drivers/usb/gadget/udc/core.c:1227 [inline]
 gadget_bind_driver+0x31c/0x684 drivers/usb/gadget/udc/core.c:1656
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x3a0/0xac4 drivers/base/dd.c:638
 __driver_probe_device+0x1c8/0x368 drivers/base/dd.c:804
 driver_probe_device+0x78/0x324 drivers/base/dd.c:834
 __driver_attach+0x3bc/0x614 drivers/base/dd.c:1220
 bus_for_each_dev+0x148/0x1d0 drivers/base/bus.c:303
 driver_attach+0x50/0x60 drivers/base/dd.c:1237
 bus_add_driver+0x2c0/0x518 drivers/base/bus.c:620
 driver_register+0x200/0x37c drivers/base/driver.c:246
 usb_gadget_register_driver_owner+0xf0/0x25c drivers/usb/gadget/udc/core.c:1730
 raw_ioctl_run drivers/usb/gadget/legacy/raw_gadget.c:549 [inline]
 raw_ioctl+0x1014/0x326c drivers/usb/gadget/legacy/raw_gadget.c:1262
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:856
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585
Code: 969f1d21 14000002 969f1d1f d343fe88 (38766908) 
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	969f1d21 	bl	0xfffffffffa7c7484
   4:	14000002 	b	0xc
   8:	969f1d1f 	bl	0xfffffffffa7c7484
   c:	d343fe88 	lsr	x8, x20, #3
* 10:	38766908 	ldrb	w8, [x8, x22] <-- trapping instruction

Crashes (41):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/25 22:39 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/25 14:16 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/25 12:59 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/25 11:29 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/28 03:57 linux-6.1.y dc5c83b7f5f8 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/27 20:24 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/27 03:08 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/27 02:02 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/26 17:27 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/26 13:17 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/26 04:45 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/26 02:43 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/25 13:04 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/25 10:21 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/24 22:21 linux-6.1.y dc5c83b7f5f8 dd737a83 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 BUG: unable to handle kernel paging request in dummy_udc_start
2026/07/28 02:45 linux-6.1.y dc5c83b7f5f8 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/28 02:45 linux-6.1.y dc5c83b7f5f8 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/28 02:44 linux-6.1.y dc5c83b7f5f8 45ae1df4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 21:55 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 19:48 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 19:47 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 15:09 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 12:37 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 12:36 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 12:35 linux-6.1.y dc5c83b7f5f8 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 05:33 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 05:33 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/27 05:33 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/26 14:53 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/26 14:38 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/26 10:55 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/26 03:55 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/26 03:53 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/26 03:53 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/25 21:59 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/25 19:18 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/25 19:11 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/25 19:10 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/25 15:51 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/25 15:48 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
2026/07/25 15:48 linux-6.1.y dc5c83b7f5f8 492bab15 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan general protection fault in dummy_udc_start
* Struck through repros no longer work on HEAD.