[moderation] [media?] general protection fault in usbtv_querycap

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: fc02acf6ac0c Merge tag 'platform-drivers-x86-v7.2-4' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=113751b9580000
kernel config: https://syzkaller.appspot.com/x/.config?x=4e38b15c29e6a1d9
dashboard link: https://syzkaller.appspot.com/bug?extid=abe640a8eb436924acf3
compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
userspace arch: i386
CC: [linux-...@vger.kernel.org linux...@vger.kernel.org mch...@kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/5daf2a14c860/disk-fc02acf6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3a2f3b89a090/vmlinux-fc02acf6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/0f67e369a20e/bzImage-fc02acf6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+abe640...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc000000000a: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000050-0x0000000000000057]
CPU: 1 UID: 0 PID: 24737 Comm: v4l_id Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:usb_make_path include/linux/usb.h:985 [inline]
RIP: 0010:usbtv_querycap+0x9c/0x100 drivers/media/usb/usbtv/usbtv-video.c:612
Code: d7 f9 49 83 c6 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 c2 2c d7 f9 4d 8b 36 4d 8d 7e 50 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 a5 2c d7 f9 48 83 c3 30 4d 8b 3f
RSP: 0000:ffffc90004f5fb10 EFLAGS: 00010206
RAX: 000000000000000a RBX: ffffc90004f5fd60 RCX: 0000000074627375
RDX: 0000000000000006 RSI: ffffffff8cd18a40 RDI: ffffc90004f5fd70
RBP: 1ffff920009ebfb6 R08: 0000000000767462 R09: 1ffff920009ebfae
R10: dffffc0000000000 R11: fffff520009ebfaf R12: dffffc0000000000
R13: ffff888020b3a0d8 R14: 0000000000000000 R15: 0000000000000050
FS: 00007f506ab68880(0000) GS:ffff88812504e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b880b1b64d CR3: 0000000021750000 CR4: 00000000003526f0
Call Trace:
<TASK>
v4l_querycap+0x236/0x470 drivers/media/v4l2-core/v4l2-ioctl.c:1106
__video_do_ioctl+0x8af/0xc70 drivers/media/v4l2-core/v4l2-ioctl.c:3133
video_usercopy+0x860/0x1430 drivers/media/v4l2-core/v4l2-ioctl.c:3475
v4l2_ioctl+0x18d/0x1e0 drivers/media/v4l2-core/v4l2-dev.c:366
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl+0xfc/0x170 fs/ioctl.c:583
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f506a51d378
Code: 00 00 48 8d 44 24 08 48 89 54 24 e0 48 89 44 24 c0 48 8d 44 24 d0 48 89 44 24 c8 b8 10 00 00 00 c7 44 24 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 07 89 d0 c3 0f 1f 40 00 48 8b 15 49 3a 0d
RSP: 002b:00007ffe752fd5e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f506a51d378
RDX: 00007ffe752fd5f0 RSI: 0000000080685600 RDI: 0000000000000003
RBP: 0000000000000002 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffe752fd7a0 R14: 00007f506ac6d000 R15: 000055b880b1f4d8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:usb_make_path include/linux/usb.h:985 [inline]
RIP: 0010:usbtv_querycap+0x9c/0x100 drivers/media/usb/usbtv/usbtv-video.c:612
Code: d7 f9 49 83 c6 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 c2 2c d7 f9 4d 8b 36 4d 8d 7e 50 4c 89 f8 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 ff e8 a5 2c d7 f9 48 83 c3 30 4d 8b 3f
RSP: 0000:ffffc90004f5fb10 EFLAGS: 00010206
RAX: 000000000000000a RBX: ffffc90004f5fd60 RCX: 0000000074627375
RDX: 0000000000000006 RSI: ffffffff8cd18a40 RDI: ffffc90004f5fd70
RBP: 1ffff920009ebfb6 R08: 0000000000767462 R09: 1ffff920009ebfae
R10: dffffc0000000000 R11: fffff520009ebfaf R12: dffffc0000000000
R13: ffff888020b3a0d8 R14: 0000000000000000 R15: 0000000000000050
FS: 00007f506ab68880(0000) GS:ffff88812504e000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00000000581d821c CR3: 0000000021750000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: d7 xlat %ds:(%rbx)
1: f9 stc
2: 49 83 c6 08 add $0x8,%r14
6: 4c 89 f0 mov %r14,%rax
9: 48 c1 e8 03 shr $0x3,%rax
d: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
12: 74 08 je 0x1c
14: 4c 89 f7 mov %r14,%rdi
17: e8 c2 2c d7 f9 call 0xf9d72cde
1c: 4d 8b 36 mov (%r14),%r14
1f: 4d 8d 7e 50 lea 0x50(%r14),%r15
23: 4c 89 f8 mov %r15,%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 ff mov %r15,%rdi
34: e8 a5 2c d7 f9 call 0xf9d72cde
39: 48 83 c3 30 add $0x30,%rbx
3d: 4d 8b 3f mov (%r15),%r15


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