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

syzbot <[email protected]> Mon, 03 Aug 2026 02:52:24 -0700
Newsgroups	org.kernel.vger.linux-usb,org.kernel.vger.linux-kernel
Message-ID	<[email protected]>
Hello,

syzbot found the following issue on:

HEAD commit:    11028ab62899 Merge tag 'probes-fixes-v7.2-rc5' of git://gi..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14759499580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=145fa60d73086782
dashboard link: https://syzkaller.appspot.com/bug?extid=fd6ef980cf1c722be639
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/dbf4cb7b4116/disk-11028ab6.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/77761f1559a8/vmlinux-11028ab6.xz
kernel image: https://storage.googleapis.com/syzbot-assets/bb1ed2bbff0e/bzImage-11028ab6.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

RSP: 002b:00007fe4435bb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fe442a25fa0 RCX: 00007fe44279df99
RDX: 00000000000001ff RSI: 0000200000000280 RDI: ffffffffffffff9c
RBP: 00007fe442834ec4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe442a26038 R14: 00007fe442a25fa0 R15: 00007ffeb0abd888
 </TASK>
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000001: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f]
CPU: 0 UID: 0 PID: 7285 Comm: syz.5.98 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:usb_put_function_instance+0x52/0xc0 drivers/usb/gadget/functions.c:76
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 67 48 8b ab 98 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d 7d 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 53 48 8d bb a8 00 00 00 48 8b 6d 08 48 b8 00 00 00
RSP: 0018:ffffc9000466fa98 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88802a5b5000 RCX: ffffc90005fc9000
RDX: 0000000000000001 RSI: ffffffff87cf0f08 RDI: 0000000000000008
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffff88802a5b5008 R15: dffffc0000000000
FS:  00007fe4435bb6c0(0000) GS:ffff888123ddc000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe4427eb680 CR3: 0000000031bb9000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 config_item_cleanup+0x146/0x240 fs/configfs/item.c:128
 config_item_release fs/configfs/item.c:137 [inline]
 kref_put include/linux/kref.h:65 [inline]
 config_item_put fs/configfs/item.c:149 [inline]
 config_item_put+0x93/0xb0 fs/configfs/item.c:146
 config_group_put include/linux/configfs.h:102 [inline]
 uvcg_attach_configfs+0x5d/0x70 drivers/usb/gadget/function/uvc_configfs.c:3832
 uvc_alloc_inst+0xaba/0xd30 drivers/usb/gadget/function/f_uvc.c:999
 try_get_usb_function_instance+0x136/0x1f0 drivers/usb/gadget/functions.c:28
 usb_get_function_instance+0x16/0x70 drivers/usb/gadget/functions.c:44
 function_make+0x18c/0x3f0 drivers/usb/gadget/configfs.c:626
 configfs_mkdir+0x51e/0xb70 fs/configfs/dir.c:1360
 vfs_mkdir+0x361/0x850 fs/namei.c:5276
 filename_mkdirat+0x48b/0x5e0 fs/namei.c:5309
 __do_sys_mkdirat fs/namei.c:5330 [inline]
 __se_sys_mkdirat fs/namei.c:5327 [inline]
 __x64_sys_mkdirat+0x89/0xc0 fs/namei.c:5327
 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: 0033:0x7fe44279df99
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:00007fe4435bb028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007fe442a25fa0 RCX: 00007fe44279df99
RDX: 00000000000001ff RSI: 0000200000000280 RDI: ffffffffffffff9c
RBP: 00007fe442834ec4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe442a26038 R14: 00007fe442a25fa0 R15: 00007ffeb0abd888
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:usb_put_function_instance+0x52/0xc0 drivers/usb/gadget/functions.c:76
Code: df 48 89 fa 48 c1 ea 03 80 3c 02 00 75 67 48 8b ab 98 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 8d 7d 08 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 53 48 8d bb a8 00 00 00 48 8b 6d 08 48 b8 00 00 00
RSP: 0018:ffffc9000466fa98 EFLAGS: 00010202

RAX: dffffc0000000000 RBX: ffff88802a5b5000 RCX: ffffc90005fc9000
RDX: 0000000000000001 RSI: ffffffff87cf0f08 RDI: 0000000000000008
----------------
Code disassembly (best guess):
   0:	df 48 89             	fisttps -0x77(%rax)
   3:	fa                   	cli
   4:	48 c1 ea 03          	shr    $0x3,%rdx
   8:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   c:	75 67                	jne    0x75
   e:	48 8b ab 98 00 00 00 	mov    0x98(%rbx),%rbp
  15:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  1c:	fc ff df
  1f:	48 8d 7d 08          	lea    0x8(%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:	75 53                	jne    0x83
  30:	48 8d bb a8 00 00 00 	lea    0xa8(%rbx),%rdi
  37:	48 8b 6d 08          	mov    0x8(%rbp),%rbp
  3b:	48                   	rex.W
  3c:	b8                   	.byte 0xb8
  3d:	00 00                	add    %al,(%rax)


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