syzbot

general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
CPU: 0 PID: 360 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
RIP: 0010:d_really_is_positive include/linux/dcache.h:499 [inline]
RIP: 0010:open_or_create_special_dir+0x89/0x1d0 fs/incfs/vfs.c:474
Code: e8 8c 42 6d ff e9 00 01 00 00 e8 82 42 6d ff 48 c7 c3 ea ff ff ff e9 ef 00 00 00 4c 89 6d d0 4c 8d 6b 30 4d 89 ef 49 c1 ef 03 <43> 80 3c 37 00 74 08 4c 89 ef e8 f8 31 a7 ff 49 83 7d 00 00 74 26
RSP: 0018:ffffc90002dd7b38 EFLAGS: 00010202
RAX: 0000000000000010 RBX: 0000000000000010 RCX: ffff88810d11bb40
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8881245b8520
RBP: ffffc90002dd7b70 R08: dffffc0000000000 R09: ffffed10248b70a5
R10: ffffed10248b70a5 R11: 1ffff110248b70a4 R12: ffff8881245b8480
R13: 0000000000000040 R14: dffffc0000000000 R15: 0000000000000008
FS:  00007fdba5c996c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdba5c98f98 CR3: 000000010f7d2000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 incfs_mount_fs+0x434/0x8c0 fs/incfs/vfs.c:1867
 legacy_get_tree+0xed/0x190 fs/fs_context.c:593
 vfs_get_tree+0x89/0x260 fs/super.c:1572
 do_new_mount+0x25a/0xa20 fs/namespace.c:2997
 path_mount+0x572/0xc80 fs/namespace.c:3327
 do_mount fs/namespace.c:3340 [inline]
 __do_sys_mount fs/namespace.c:3548 [inline]
 __se_sys_mount+0x318/0x380 fs/namespace.c:3525
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3525
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7fdba5e49ec9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fdba5c99038 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fdba60a1090 RCX: 00007fdba5e49ec9
RDX: 0000200000000180 RSI: 0000200000000080 RDI: 0000200000000000
RBP: 00007fdba5eccf91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fdba60a1128 R14: 00007fdba60a1090 R15: 00007ffc2a948d58
Modules linked in:
---[ end trace 9d1f5f38dbb5797d ]---
RIP: 0010:d_really_is_positive include/linux/dcache.h:499 [inline]
RIP: 0010:open_or_create_special_dir+0x89/0x1d0 fs/incfs/vfs.c:474
Code: e8 8c 42 6d ff e9 00 01 00 00 e8 82 42 6d ff 48 c7 c3 ea ff ff ff e9 ef 00 00 00 4c 89 6d d0 4c 8d 6b 30 4d 89 ef 49 c1 ef 03 <43> 80 3c 37 00 74 08 4c 89 ef e8 f8 31 a7 ff 49 83 7d 00 00 74 26
RSP: 0018:ffffc90002dd7b38 EFLAGS: 00010202
RAX: 0000000000000010 RBX: 0000000000000010 RCX: ffff88810d11bb40
RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffff8881245b8520
RBP: ffffc90002dd7b70 R08: dffffc0000000000 R09: ffffed10248b70a5
R10: ffffed10248b70a5 R11: 1ffff110248b70a4 R12: ffff8881245b8480
R13: 0000000000000040 R14: dffffc0000000000 R15: 0000000000000008
FS:  00007fdba5c996c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fdba5c98f98 CR3: 000000010f7d2000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	e8 8c 42 6d ff       	call   0xff6d4291
   5:	e9 00 01 00 00       	jmp    0x10a
   a:	e8 82 42 6d ff       	call   0xff6d4291
   f:	48 c7 c3 ea ff ff ff 	mov    $0xffffffffffffffea,%rbx
  16:	e9 ef 00 00 00       	jmp    0x10a
  1b:	4c 89 6d d0          	mov    %r13,-0x30(%rbp)
  1f:	4c 8d 6b 30          	lea    0x30(%rbx),%r13
  23:	4d 89 ef             	mov    %r13,%r15
  26:	49 c1 ef 03          	shr    $0x3,%r15
* 2a:	43 80 3c 37 00       	cmpb   $0x0,(%r15,%r14,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 ef             	mov    %r13,%rdi
  34:	e8 f8 31 a7 ff       	call   0xffa73231
  39:	49 83 7d 00 00       	cmpq   $0x0,0x0(%r13)
  3e:	74 26                	je     0x66