general protection fault in usbtest_probe

Status: upstream: reported C repro on 2026/07/24 21:55
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+7758c8610ba9859769d6@syzkaller.appspotmail.com
First crash: 5d20h, last: 3h00m
▶ ▼ Bug presence (1)
Date Name Commit Repro Result
2026/07/25 upstream (ToT) 3dab139d4795 C [report] general protection fault in usbtest_probe
▶ ▼ Similar bugs (2)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in usbtest_probe usb prio:low 8 syz, C 13 1d22h 1d18h 0/29 upstream: reported C repro on 2026/07/29 00:19
linux-6.1 BUG: unable to handle kernel paging request in usbtest_probe 8 5 5d17h 5d18h 0/3 upstream: reported on 2026/07/24 23:34

Sample crash report:
usb 1-1: New USB device found, idVendor=0547, idProduct=2235, bcdDevice= 0.00
usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
usb 1-1: Product: syz
usb 1-1: Manufacturer: syz
usb 1-1: SerialNumber: syz
general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 PID: 13 Comm: kworker/0:1 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:usbtest_probe+0x516/0xcb0 drivers/usb/misc/usbtest.c:2821
Code: 50 fb 45 85 ff 78 0a e8 e8 76 50 fb e9 92 00 00 00 48 8b 04 24 4c 8d 78 0a 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 0f 85 bf 06 00 00 45 0f b6 3f 44 89 fe 83 e6 01
RSP: 0018:ffffc90000d26fc0 EFLAGS: 00010202
RAX: 0000000000000001 RBX: ffff888072927000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 00000000ffffffff
RBP: 1ffff11003ee7d1b R08: 000000000000001c R09: ffffffff810047ff
R10: 0000000000000002 R11: 00000000afa6265f R12: ffff88801f73e800
R13: 1ffff11003ee7d00 R14: ffff88801f73e8d8 R15: 000000000000000a
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055aa82b21ee0 CR3: 0000000075308000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 usb_probe_interface+0x5be/0xae0 drivers/usb/core/driver.c:396
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x276/0xc70 drivers/base/dd.c:595
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:775
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:805
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:927
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a7/0x480 drivers/base/dd.c:999
 bus_probe_device+0xba/0x1d0 drivers/base/bus.c:489
 device_add+0xbcf/0x1050 drivers/base/core.c:3427
 usb_set_configuration+0x19d5/0x2030 drivers/usb/core/message.c:2223
 usb_generic_driver_probe+0x89/0x150 drivers/usb/core/generic.c:238
 usb_probe_device+0x126/0x250 drivers/usb/core/driver.c:293
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x276/0xc70 drivers/base/dd.c:595
 __driver_probe_device+0x1f5/0x390 drivers/base/dd.c:775
 driver_probe_device+0x4f/0x420 drivers/base/dd.c:805
 __device_attach_driver+0x2b0/0x500 drivers/base/dd.c:927
 bus_for_each_drv+0x184/0x210 drivers/base/bus.c:429
 __device_attach+0x2a7/0x480 drivers/base/dd.c:999
 bus_probe_device+0xba/0x1d0 drivers/base/bus.c:489
 device_add+0xbcf/0x1050 drivers/base/core.c:3427
 usb_new_device+0x9f6/0x15d0 drivers/usb/core/hub.c:2632
 hub_port_connect drivers/usb/core/hub.c:5497 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5637 [inline]
 port_event drivers/usb/core/hub.c:5799 [inline]
 hub_event+0x2b8d/0x5260 drivers/usb/core/hub.c:5881
 process_one_work+0x867/0xff0 kernel/workqueue.c:2310
 worker_thread+0xad7/0x12a0 kernel/workqueue.c:2457
 kthread+0x42e/0x520 kernel/kthread.c:334
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>
Modules linked in:
---[ end trace 791dcb4553028a2a ]---
RIP: 0010:usbtest_probe+0x516/0xcb0 drivers/usb/misc/usbtest.c:2821
Code: 50 fb 45 85 ff 78 0a e8 e8 76 50 fb e9 92 00 00 00 48 8b 04 24 4c 8d 78 0a 4c 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <0f> b6 04 08 84 c0 0f 85 bf 06 00 00 45 0f b6 3f 44 89 fe 83 e6 01
RSP: 0018:ffffc90000d26fc0 EFLAGS: 00010202
RAX: 0000000000000001 RBX: ffff888072927000 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 00000000ffffffff RDI: 00000000ffffffff
RBP: 1ffff11003ee7d1b R08: 000000000000001c R09: ffffffff810047ff
R10: 0000000000000002 R11: 00000000afa6265f R12: ffff88801f73e800
R13: 1ffff11003ee7d00 R14: ffff88801f73e8d8 R15: 000000000000000a
FS:  0000000000000000(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055aa82b21ee0 CR3: 0000000075308000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	50                   	push   %rax
   1:	fb                   	sti
   2:	45 85 ff             	test   %r15d,%r15d
   5:	78 0a                	js     0x11
   7:	e8 e8 76 50 fb       	call   0xfb5076f4
   c:	e9 92 00 00 00       	jmp    0xa3
  11:	48 8b 04 24          	mov    (%rsp),%rax
  15:	4c 8d 78 0a          	lea    0xa(%rax),%r15
  19:	4c 89 f8             	mov    %r15,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	0f b6 04 08          	movzbl (%rax,%rcx,1),%eax <-- trapping instruction
  2e:	84 c0                	test   %al,%al
  30:	0f 85 bf 06 00 00    	jne    0x6f5
  36:	45 0f b6 3f          	movzbl (%r15),%r15d
  3a:	44 89 fe             	mov    %r15d,%esi
  3d:	83 e6 01             	and    $0x1,%esi

Crashes (7):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/25 12:04 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 usbtest_probe
2026/07/30 15:31 linux-5.15.y 6e2fd6534337 2377cd3d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in usbtest_probe
2026/07/27 15:02 linux-5.15.y 674f684f7c61 aae9036b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in usbtest_probe
2026/07/25 04:42 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 usbtest_probe
2026/07/25 04:42 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 usbtest_probe
2026/07/25 04:39 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 usbtest_probe
2026/07/24 21:55 linux-5.15.y 674f684f7c61 dd737a83 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in usbtest_probe
* Struck through repros no longer work on HEAD.