syzbot

general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 0 PID: 373 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:d_really_is_positive include/linux/dcache.h:503 [inline]
RIP: 0010:open_or_create_special_dir+0x85/0x1f0 fs/incfs/vfs.c:480
Code: 1b e8 cf 91 64 ff e9 21 01 00 00 e8 c5 91 64 ff 48 c7 c3 ea ff ff ff e9 10 01 00 00 4c 89 f0 4c 8d 73 30 4d 89 f7 49 c1 ef 03 <41> 80 3c 07 00 74 08 4c 89 f7 e8 ac 02 a4 ff 49 83 3e 00 74 2c e8
RSP: 0018:ffffc90000b87b00 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000008 RCX: ffff88811071cf00
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 00000000ffffffff
RBP: ffffc90000b87b30 R08: ffff8881223b80a7 R09: 1ffff11024477014
R10: dffffc0000000000 R11: ffffed1024477015 R12: ffff8881223b8000
R13: ffffc90000b87b7f R14: 0000000000000038 R15: 0000000000000007
FS:  00007fbc40f306c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbc40f0eff8 CR3: 000000012eed8000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 incfs_mount_fs+0x42f/0x890 fs/incfs/vfs.c:1884
 legacy_get_tree+0xed/0x190 fs/fs_context.c:611
 vfs_get_tree+0x89/0x260 fs/super.c:1530
 do_new_mount+0x251/0xb40 fs/namespace.c:3037
 path_mount+0x640/0xff0 fs/namespace.c:3367
 do_mount fs/namespace.c:3380 [inline]
 __do_sys_mount fs/namespace.c:3588 [inline]
 __se_sys_mount+0x320/0x390 fs/namespace.c:3565
 __x64_sys_mount+0xbf/0xd0 fs/namespace.c:3565
 x64_sys_call+0x6bf/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7fbc410cee59
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:00007fbc40f30028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fbc41356fa0 RCX: 00007fbc410cee59
RDX: 0000200000000200 RSI: 0000200000000140 RDI: 0000200000000000
RBP: 00007fbc41164e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000082 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbc41357038 R14: 00007fbc41356fa0 R15: 00007fff34a5d3e8
 </TASK>
Modules linked in:
---[ end trace e76b79a5580649b2 ]---
RIP: 0010:d_really_is_positive include/linux/dcache.h:503 [inline]
RIP: 0010:open_or_create_special_dir+0x85/0x1f0 fs/incfs/vfs.c:480
Code: 1b e8 cf 91 64 ff e9 21 01 00 00 e8 c5 91 64 ff 48 c7 c3 ea ff ff ff e9 10 01 00 00 4c 89 f0 4c 8d 73 30 4d 89 f7 49 c1 ef 03 <41> 80 3c 07 00 74 08 4c 89 f7 e8 ac 02 a4 ff 49 83 3e 00 74 2c e8
RSP: 0018:ffffc90000b87b00 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000008 RCX: ffff88811071cf00
RDX: 0000000000000000 RSI: 0000000000000008 RDI: 00000000ffffffff
RBP: ffffc90000b87b30 R08: ffff8881223b80a7 R09: 1ffff11024477014
R10: dffffc0000000000 R11: ffffed1024477015 R12: ffff8881223b8000
R13: ffffc90000b87b7f R14: 0000000000000038 R15: 0000000000000007
FS:  00007fbc40f306c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbc40f0eff8 CR3: 000000012eed8000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	1b e8                	sbb    %eax,%ebp
   2:	cf                   	iret
   3:	91                   	xchg   %eax,%ecx
   4:	64 ff                	fs ljmp (bad)
   6:	e9 21 01 00 00       	jmp    0x12c
   b:	e8 c5 91 64 ff       	call   0xff6491d5
  10:	48 c7 c3 ea ff ff ff 	mov    $0xffffffffffffffea,%rbx
  17:	e9 10 01 00 00       	jmp    0x12c
  1c:	4c 89 f0             	mov    %r14,%rax
  1f:	4c 8d 73 30          	lea    0x30(%rbx),%r14
  23:	4d 89 f7             	mov    %r14,%r15
  26:	49 c1 ef 03          	shr    $0x3,%r15
* 2a:	41 80 3c 07 00       	cmpb   $0x0,(%r15,%rax,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 f7             	mov    %r14,%rdi
  34:	e8 ac 02 a4 ff       	call   0xffa402e5
  39:	49 83 3e 00          	cmpq   $0x0,(%r14)
  3d:	74 2c                	je     0x6b
  3f:	e8                   	.byte 0xe8