Re: [syzbot] [usb?] general protection fault in usb_gadget_udc_reset (4)

[syzbot <syzbot+19bed92c97bee999e5db@syzkaller.appspotmail.com>]

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
general protection fault in usb_gadget_udc_reset

raw-gadget.1 gadget.3: Inc usage: 1 A
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
CPU: 1 UID: 0 PID: 5926 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/27/2026
Workqueue: usb_hub_wq hub_event
RIP: 0010:usb_gadget_udc_reset+0x27/0x60 drivers/usb/gadget/udc/core.c:1200
Code: 90 90 90 f3 0f 1e fa 41 56 53 49 89 f6 48 89 fb e8 6e 5c c0 fa 49 83 c6 40 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 cb 74 26 fb 4d 8b 1e 48 89 df 2e e8
RSP: 0018:ffffc90004197310 EFLAGS: 00010202
RAX: 0000000000000008 RBX: ffff888029ce8c40 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff8f6a51b7 R09: 1ffffffff1ed4a36
R10: dffffc0000000000 R11: ffffffff8b2104d0 R12: 1ffff1100539d187
R13: ffff8880296b450b R14: 0000000000000040 R15: ffff888029ce8c40
FS:  0000000000000000(0000) GS:ffff88812643d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f21940fcff8 CR3: 0000000038eda000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 set_link_state+0xa17/0x10c0 drivers/usb/gadget/udc/dummy_hcd.c:474
 dummy_hub_control+0xa09/0x1a00 drivers/usb/gadget/udc/dummy_hcd.c:-1
 rh_call_control drivers/usb/core/hcd.c:652 [inline]
 rh_urb_enqueue drivers/usb/core/hcd.c:817 [inline]
 usb_hcd_submit_urb+0xdbe/0x1b50 drivers/usb/core/hcd.c:1538
 usb_start_wait_urb+0x12b/0x510 drivers/usb/core/message.c:59
 usb_internal_control_msg drivers/usb/core/message.c:103 [inline]
 usb_control_msg+0x232/0x3e0 drivers/usb/core/message.c:154
 set_port_feature drivers/usb/core/hub.c:466 [inline]
 hub_port_reset+0x3c7/0x1820 drivers/usb/core/hub.c:3083
 hub_port_init+0x299/0x28c0 drivers/usb/core/hub.c:4939
 hub_port_connect drivers/usb/core/hub.c:5496 [inline]
 hub_port_connect_change drivers/usb/core/hub.c:5707 [inline]
 port_event drivers/usb/core/hub.c:5871 [inline]
 hub_event+0x25d3/0x4f60 drivers/usb/core/hub.c:5953
 process_one_work kernel/workqueue.c:3275 [inline]
 process_scheduled_works+0xb02/0x1830 kernel/workqueue.c:3358
 worker_thread+0xa50/0xfc0 kernel/workqueue.c:3439
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:usb_gadget_udc_reset+0x27/0x60 drivers/usb/gadget/udc/core.c:1200
Code: 90 90 90 f3 0f 1e fa 41 56 53 49 89 f6 48 89 fb e8 6e 5c c0 fa 49 83 c6 40 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 cb 74 26 fb 4d 8b 1e 48 89 df 2e e8
RSP: 0018:ffffc90004197310 EFLAGS: 00010202
RAX: 0000000000000008 RBX: ffff888029ce8c40 RCX: dffffc0000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: ffffffff8f6a51b7 R09: 1ffffffff1ed4a36
R10: dffffc0000000000 R11: ffffffff8b2104d0 R12: 1ffff1100539d187
R13: ffff8880296b450b R14: 0000000000000040 R15: ffff888029ce8c40
FS:  0000000000000000(0000) GS:ffff88812643d000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f21940fcff8 CR3: 00000000348ae000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	90                   	nop
   2:	90                   	nop
   3:	f3 0f 1e fa          	endbr64
   7:	41 56                	push   %r14
   9:	53                   	push   %rbx
   a:	49 89 f6             	mov    %rsi,%r14
   d:	48 89 fb             	mov    %rdi,%rbx
  10:	e8 6e 5c c0 fa       	call   0xfac05c83
  15:	49 83 c6 40          	add    $0x40,%r14
  19:	4c 89 f0             	mov    %r14,%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:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 f7             	mov    %r14,%rdi
  33:	e8 cb 74 26 fb       	call   0xfb267503
  38:	4d 8b 1e             	mov    (%r14),%r11
  3b:	48 89 df             	mov    %rbx,%rdi
  3e:	2e                   	cs
  3f:	e8                   	.byte 0xe8


Tested on:

commit:         65169048 Merge tag 'spi-fix-v7.0-rc2' of git://git.ker..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
console output: https://syzkaller.appspot.com/x/log.txt?x=153e775a580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=2a019678b1a3a692
dashboard link: https://syzkaller.appspot.com/bug?extid=19bed92c97bee999e5db
compiler:       Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=162dd75a580000