[syzbot] [usb?] general protection fault in uvcg_video_init

[syzbot] [usb?] general protection fault in uvcg_video_init

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    62cc90241548 Merge tag 'mm-hotfixes-stable-2026-07-27-14-1..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=175316b9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=145fa60d73086782
dashboard link: https://syzkaller.appspot.com/bug?extid=8dcac923582c28505fd7
compiler:       gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/824c8ce85a0f/disk-62cc9024.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a1e6cc0e8f11/vmlinux-62cc9024.xz
kernel image: https://storage.googleapis.com/syzbot-assets/807679f73b90/bzImage-62cc9024.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8dcac923582c28505fd7@syzkaller.appspotmail.com

configfs-gadget.g1 gadget.32: uvc: uvc_function_bind()
Oops: general protection fault, probably for non-canonical address 0xdffffc00000000ec: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000760-0x0000000000000767]
CPU: 1 UID: 0 PID: 8101 Comm: syz.4.604 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:uvcg_video_init.cold+0x5f/0x135 drivers/usb/gadget/function/uvc_video.c:824
Code: e0 2a 80 3c 02 00 74 08 48 89 df e8 6a bd 25 01 48 8b 2b b8 ff ff 37 00 48 c1 e0 2a 48 8d bd 60 07 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 b1 00 00 00 48 8d bd 90 07 00 00 b8 ff ff 37 00
RSP: 0000:ffffc9000d2d7878 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888055368840 RCX: ffffc900065b2000
RDX: 00000000000000ec RSI: ffffffff81552b56 RDI: 0000000000000760
RBP: 0000000000000000 R08: 0000000000000007 R09: fffffffffffff000
R10: fffffffffffffffc R11: ffffffff8bba81c5 R12: ffff8880553688a0
R13: 0000000000000003 R14: ffff8880553686a0 R15: ffff88804c7c6528
FS:  00007f59706d16c0(0000) GS:ffff888123edc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c379612 CR3: 0000000022a85000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 uvc_function_bind+0x136e/0x1939 drivers/usb/gadget/function/f_uvc.c:874
 usb_add_function+0x219/0x890 drivers/usb/gadget/composite.c:333
 configfs_composite_bind+0xd83/0x1960 drivers/usb/gadget/configfs.c:1802
 gadget_bind_driver+0x28c/0xbf0 drivers/usb/gadget/udc/core.c:1662
 call_driver_probe drivers/base/dd.c:628 [inline]
 really_probe+0x241/0xa60 drivers/base/dd.c:706
 __driver_probe_device+0x20e/0x450 drivers/base/dd.c:868
 driver_probe_device+0x4a/0x140 drivers/base/dd.c:898
 __driver_attach+0x21f/0x5b0 drivers/base/dd.c:1292
 bus_for_each_dev+0x13e/0x1d0 drivers/base/bus.c:383
 bus_add_driver+0x305/0x5b0 drivers/base/bus.c:763
 driver_register+0x1e2/0x360 drivers/base/driver.c:174
 usb_gadget_register_driver_owner+0x132/0x210 drivers/usb/gadget/udc/core.c:1752
 gadget_dev_desc_UDC_store+0x1b0/0x2e0 drivers/usb/gadget/configfs.c:300
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x302/0x4e0 fs/configfs/file.c:229
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x6ac/0x1050 fs/read_write.c:687
 ksys_write+0x12a/0x250 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x115/0x870 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f596f79de99
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:00007f59706d1028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f596fa25fa0 RCX: 00007f596f79de99
RDX: 000000000000000c RSI: 0000200000001f00 RDI: 0000000000000004
RBP: 00007f596f833eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f596fa26038 R14: 00007f596fa25fa0 R15: 00007ffed2857f28
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:uvcg_video_init.cold+0x5f/0x135 drivers/usb/gadget/function/uvc_video.c:824
Code: e0 2a 80 3c 02 00 74 08 48 89 df e8 6a bd 25 01 48 8b 2b b8 ff ff 37 00 48 c1 e0 2a 48 8d bd 60 07 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 b1 00 00 00 48 8d bd 90 07 00 00 b8 ff ff 37 00
RSP: 0000:ffffc9000d2d7878 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff888055368840 RCX: ffffc900065b2000
RDX: 00000000000000ec RSI: ffffffff81552b56 RDI: 0000000000000760
RBP: 0000000000000000 R08: 0000000000000007 R09: fffffffffffff000
R10: fffffffffffffffc R11: ffffffff8bba81c5 R12: ffff8880553688a0
R13: 0000000000000003 R14: ffff8880553686a0 R15: ffff88804c7c6528
FS:  00007f59706d16c0(0000) GS:ffff888123ddc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055558731aa48 CR3: 0000000022a85000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	e0 2a                	loopne 0x2c
   2:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   6:	74 08                	je     0x10
   8:	48 89 df             	mov    %rbx,%rdi
   b:	e8 6a bd 25 01       	call   0x125bd7a
  10:	48 8b 2b             	mov    (%rbx),%rbp
  13:	b8 ff ff 37 00       	mov    $0x37ffff,%eax
  18:	48 c1 e0 2a          	shl    $0x2a,%rax
  1c:	48 8d bd 60 07 00 00 	lea    0x760(%rbp),%rdi
  23:	48 89 fa             	mov    %rdi,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
* 2a:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2e:	0f 85 b1 00 00 00    	jne    0xe5
  34:	48 8d bd 90 07 00 00 	lea    0x790(%rbp),%rdi
  3b:	b8 ff ff 37 00       	mov    $0x37ffff,%eax


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