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

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3eb40771c00a Merge tag 'soc-fixes-7.2-3' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11b7ba79580000
kernel config: https://syzkaller.appspot.com/x/.config?x=2ca5f2f2c4197664
dashboard link: https://syzkaller.appspot.com/bug?extid=37a57a84893052ab6071
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=15009949580000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+37a57a...@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: 5878 Comm: syz-executor121 Not tainted syzkaller #0 PREEMPT(full)
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: d9 f9 49 83 c6 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 42 3b d9 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 25 3b d9 f9 48 83 c3 30 4d 8b 3f
RSP: 0018:ffffc90003757b10 EFLAGS: 00010206
RAX: 000000000000000a RBX: ffffc90003757d60 RCX: 0000000074627375
RDX: 0000000000000006 RSI: ffffffff8cd143a0 RDI: ffffc90003757d70
RBP: 1ffff920006eafb6 R08: 0000000000767462 R09: 1ffff920006eafae
R10: dffffc0000000000 R11: fffff520006eafaf R12: dffffc0000000000
R13: ffff888035e170d8 R14: 0000000000000000 R15: 0000000000000050
FS: 00007f7ef67fc6c0(0000) GS:ffff888125049000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c7f8b42d51 CR3: 0000000071dc6000 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: 0033:0x7f7efcf7300b
Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00
RSP: 002b:00007f7ef67fc120 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000080685600 RCX: 00007f7efcf7300b
RDX: 00007f7ef67fc190 RSI: 0000000080685600 RDI: 0000000000000006
RBP: 0000000000000021 R08: 0000000000000002 R09: 0000000000000000
R10: 00007f7efcfe37e0 R11: 0000000000000246 R12: ffffffffffffffd0
R13: 0000000000000000 R14: 00007ffc6b9d1890 R15: 00007ffc6b9d1978
</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: d9 f9 49 83 c6 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 42 3b d9 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 25 3b d9 f9 48 83 c3 30 4d 8b 3f
RSP: 0018:ffffc90003757b10 EFLAGS: 00010206
RAX: 000000000000000a RBX: ffffc90003757d60 RCX: 0000000074627375
RDX: 0000000000000006 RSI: ffffffff8cd143a0 RDI: ffffc90003757d70
RBP: 1ffff920006eafb6 R08: 0000000000767462 R09: 1ffff920006eafae
R10: dffffc0000000000 R11: fffff520006eafaf R12: dffffc0000000000
R13: ffff888035e170d8 R14: 0000000000000000 R15: 0000000000000050
FS: 00007f7ef67fc6c0(0000) GS:ffff888125049000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055c7f8b42d51 CR3: 0000000071dc6000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: d9 f9 fyl2xp1
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 42 3b d9 f9 call 0xf9d93b5e
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 25 3b d9 f9 call 0xf9d93b5e
39: 48 83 c3 30 add $0x30,%rbx
3d: 4d 8b 3f mov (%r15),%r15


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