Re: [syzbot] [usb?] general protection fault in vhci_hcd_probe

[syzbot <syzbot+7300affe388249d66dfe@syzkaller.appspotmail.com>]

syzbot has found a reproducer for the following issue on:

HEAD commit:    9d80aa4617b3 Add linux-next specific files for 20260903
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
console output: https://syzkaller.appspot.com/x/log.txt?x=10adf4f9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=bb4a32c282cc2ec7
dashboard link: https://syzkaller.appspot.com/bug?extid=7300affe388249d66dfe
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=121c7215580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+7300affe388249d66dfe@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 6482 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:vhci_hcd_probe+0x47/0x3e0 drivers/usb/usbip/vhci_hcd.c:1367
Code: 0f ee e4 f9 49 8d 9e 80 00 00 00 48 89 d8 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 13 17 55 fa 48 8b 1b 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 08 48 89 df e8 fb 16 55 fa 4c 8b 23 48 c7 c0 80 6c
RSP: 0018:ffffc900033c7ac0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888076a89f40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88801c7a6000
RBP: dffffc0000000000 R08: ffff88802af3ba53 R09: 1ffff110055e774a
R10: dffffc0000000000 R11: ffffffff87e2e6c0 R12: ffff88801c7a6000
R13: ffffffff8fc7ad20 R14: ffff88801c7a6000 R15: ffffffff87e2e6c0
FS:  00007f21f99fe6c0(0000) GS:ffff888124dc0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f21fa270000 CR3: 000000007f704000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 platform_probe+0xf9/0x190 drivers/base/platform.c:1507
 call_driver_probe drivers/base/dd.c:-1 [inline]
 really_probe+0x254/0xae0 drivers/base/dd.c:706
 __driver_probe_device+0x1e8/0x360 drivers/base/dd.c:868
 device_driver_attach+0xe0/0x1d0 drivers/base/dd.c:1203
 bind_store+0x1d0/0x220 drivers/base/bus.c:267
 kernfs_fop_write_iter+0x3a4/0x540 fs/kernfs/file.c:345
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x612/0xba0 fs/read_write.c:687
 ksys_write+0x150/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f21fa39e0d9
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:00007f21f99fe028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f21fa625fa0 RCX: 00007f21fa39e0d9
RDX: 0000000000000006 RSI: 00002000000000c0 RDI: 0000000000000004
RBP: 00007f21fa435024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f21fa626038 R14: 00007f21fa625fa0 R15: 00007fff742f7888
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:vhci_hcd_probe+0x47/0x3e0 drivers/usb/usbip/vhci_hcd.c:1367
Code: 0f ee e4 f9 49 8d 9e 80 00 00 00 48 89 d8 48 c1 e8 03 80 3c 28 00 74 08 48 89 df e8 13 17 55 fa 48 8b 1b 48 89 d8 48 c1 e8 03 <80> 3c 28 00 74 08 48 89 df e8 fb 16 55 fa 4c 8b 23 48 c7 c0 80 6c
RSP: 0018:ffffc900033c7ac0 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff888076a89f40
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88801c7a6000
RBP: dffffc0000000000 R08: ffff88802af3ba53 R09: 1ffff110055e774a
R10: dffffc0000000000 R11: ffffffff87e2e6c0 R12: ffff88801c7a6000
R13: ffffffff8fc7ad20 R14: ffff88801c7a6000 R15: ffffffff87e2e6c0
FS:  00007f21f99fe6c0(0000) GS:ffff888124cc0000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b34124008 CR3: 000000007f704000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	0f ee e4             	pmaxsw %mm4,%mm4
   3:	f9                   	stc
   4:	49 8d 9e 80 00 00 00 	lea    0x80(%r14),%rbx
   b:	48 89 d8             	mov    %rbx,%rax
   e:	48 c1 e8 03          	shr    $0x3,%rax
  12:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1)
  16:	74 08                	je     0x20
  18:	48 89 df             	mov    %rbx,%rdi
  1b:	e8 13 17 55 fa       	call   0xfa551733
  20:	48 8b 1b             	mov    (%rbx),%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	80 3c 28 00          	cmpb   $0x0,(%rax,%rbp,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	48 89 df             	mov    %rbx,%rdi
  33:	e8 fb 16 55 fa       	call   0xfa551733
  38:	4c 8b 23             	mov    (%rbx),%r12
  3b:	48                   	rex.W
  3c:	c7                   	.byte 0xc7
  3d:	c0                   	.byte 0xc0
  3e:	80                   	.byte 0x80
  3f:	6c                   	insb   (%dx),%es:(%rdi)


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