[syzbot] [fs?] general protection fault in configfs_depend_item_unlocked

[syzbot <syzbot+a9efa71b884a23e74153@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    1fc5a74b108f Merge tag 'kmalloc_obj-v7.3-rc2' of git://git..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17299b49580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b454dc6b1b7acd30
dashboard link: https://syzkaller.appspot.com/bug?extid=a9efa71b884a23e74153
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/90e25e7ccbef/disk-1fc5a74b.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4e7b78b56aee/vmlinux-1fc5a74b.xz
kernel image: https://storage.googleapis.com/syzbot-assets/c2f010471672/bzImage-1fc5a74b.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+a9efa71b884a23e74153@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc000000000c: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000060-0x0000000000000067]
CPU: 1 UID: 0 PID: 6141 Comm: syz.3.68 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:configfs_depend_item_unlocked+0x96/0x420 fs/configfs/dir.c:1246
Code: df e8 1e 88 00 00 89 c5 31 ff 89 c6 e8 13 58 56 ff 85 ed 74 0a e8 fa 52 56 ff 4d 89 fd eb 6c 48 8d 7b 60 48 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 05 e8 ee 0f c2 ff 4c 8b 6b 60 48 89 df e8 e2 87
RSP: 0018:ffffc90005477ad8 EFLAGS: 00010206
RAX: 000000000000000c RBX: 0000000000000000 RCX: ffff888026a51f40
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000060
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f63c30 R12: ffffffff8ecb12e0
R13: 1ffff92000a8ef6c R14: dffffc0000000000 R15: ffff888061ee3c00
FS:  00007ff7e9de66c0(0000) GS:ffff888125cd4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00002000000016c0 CR3: 000000005eb6a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 usbg_make_tpg+0x1e0/0x550 drivers/usb/gadget/function/f_tcm.c:1692
 target_fabric_make_tpg+0xa8/0x6d0 drivers/target/target_core_fabric_configfs.c:947
 configfs_mkdir+0x4f6/0x9e0 fs/configfs/dir.c:1360
 vfs_mkdir+0x408/0x620 fs/namei.c:5410
 filename_mkdirat+0x289/0x520 fs/namei.c:5443
 __do_sys_mkdir fs/namei.c:5470 [inline]
 __se_sys_mkdir+0x34/0x150 fs/namei.c:5467
 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: 0033:0x7ff7ebb8e159
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:00007ff7e9de6028 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007ff7ebe15fa0 RCX: 00007ff7ebb8e159
RDX: 0000000000000000 RSI: 00000000000001ff RDI: 0000200000000600
RBP: 00007ff7ebc25024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ff7ebe16038 R14: 00007ff7ebe15fa0 R15: 00007ffc34b91458
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:configfs_depend_item_unlocked+0x96/0x420 fs/configfs/dir.c:1246
Code: df e8 1e 88 00 00 89 c5 31 ff 89 c6 e8 13 58 56 ff 85 ed 74 0a e8 fa 52 56 ff 4d 89 fd eb 6c 48 8d 7b 60 48 89 f8 48 c1 e8 03 <42> 80 3c 30 00 74 05 e8 ee 0f c2 ff 4c 8b 6b 60 48 89 df e8 e2 87
RSP: 0018:ffffc90005477ad8 EFLAGS: 00010206
RAX: 000000000000000c RBX: 0000000000000000 RCX: ffff888026a51f40
RDX: 0000000000000002 RSI: 0000000000000000 RDI: 0000000000000060
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f63c30 R12: ffffffff8ecb12e0
R13: 1ffff92000a8ef6c R14: dffffc0000000000 R15: ffff888061ee3c00
FS:  00007ff7e9de66c0(0000) GS:ffff888125cd4000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005650aabe2588 CR3: 000000005eb6a000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	e8 1e 88 00 00       	call   0x8823
   5:	89 c5                	mov    %eax,%ebp
   7:	31 ff                	xor    %edi,%edi
   9:	89 c6                	mov    %eax,%esi
   b:	e8 13 58 56 ff       	call   0xff565823
  10:	85 ed                	test   %ebp,%ebp
  12:	74 0a                	je     0x1e
  14:	e8 fa 52 56 ff       	call   0xff565313
  19:	4d 89 fd             	mov    %r15,%r13
  1c:	eb 6c                	jmp    0x8a
  1e:	48 8d 7b 60          	lea    0x60(%rbx),%rdi
  22:	48 89 f8             	mov    %rdi,%rax
  25:	48 c1 e8 03          	shr    $0x3,%rax
* 29:	42 80 3c 30 00       	cmpb   $0x0,(%rax,%r14,1) <-- trapping instruction
  2e:	74 05                	je     0x35
  30:	e8 ee 0f c2 ff       	call   0xffc21023
  35:	4c 8b 6b 60          	mov    0x60(%rbx),%r13
  39:	48 89 df             	mov    %rbx,%rdi
  3c:	e8                   	.byte 0xe8
  3d:	e2 87                	loop   0xffffffc6


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