incfs: ino conflict with backing FS 2
overlayfs: failed to create directory ./bus/work (errno: 22); mounting read-only
general protection fault, probably for non-canonical address 0xdffffc000000000a: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000050-0x0000000000000057]
CPU: 0 PID: 3536 Comm: syz.4.697 Tainted: G        W          syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/16/2026
RIP: 0010:mnt_add_count fs/namespace.c:179 [inline]
RIP: 0010:mntget+0x2e/0x60 fs/namespace.c:1296
Code: 41 56 53 48 89 fb e8 41 95 a9 ff 48 85 db 74 30 e8 37 95 a9 ff 4c 8d 73 50 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 c4 1f ef ff 49 8b 06 65 ff 00 eb 05
RSP: 0018:ffffc9000e5b7400 EFLAGS: 00010206
RAX: 000000000000000a RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffffc90003a13000 RSI: 00000000000022dd RDI: 00000000000022de
RBP: ffffc9000e5b7410 R08: ffffc9000e5b74af R09: 1ffff92001cb6e95
R10: dffffc0000000000 R11: fffff52001cb6e96 R12: 0000000000000000
R13: ffffc9000e5b7401 R14: 0000000000000051 R15: ffffc9000e5b74a0
FS:  00007f50b0f566c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fca0c26e000 CR3: 000000013532d000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 path_get+0x37/0x80 fs/namei.c:547
 get_incfs_backing_path fs/incfs/data_mgmt.h:541 [inline]
 file_open+0x1e3/0x680 fs/incfs/vfs.c:1496
 do_dentry_open+0x885/0x11f0 fs/open.c:884
 open_with_fake_path+0x5a/0x90 fs/open.c:1093
 ovl_open_realfile+0x20c/0x290 fs/overlayfs/file.c:66
 ovl_open+0x168/0x2e0 fs/overlayfs/file.c:163
 do_dentry_open+0x885/0x11f0 fs/open.c:884
 vfs_open+0x73/0x80 fs/open.c:1017
 do_open fs/namei.c:3633 [inline]
 path_openat+0x2699/0x2f30 fs/namei.c:3790
 do_filp_open+0x1ee/0x420 fs/namei.c:3817
 do_open_execat+0x14a/0xaa0 fs/exec.c:931
 bprm_execve+0x40f/0x1390 fs/exec.c:1853
 do_execveat_common+0x8e3/0xaa0 fs/exec.c:1983
 do_execve fs/exec.c:2057 [inline]
 __do_sys_execve fs/exec.c:2133 [inline]
 __se_sys_execve fs/exec.c:2128 [inline]
 __x64_sys_execve+0x92/0xb0 fs/exec.c:2128
 x64_sys_call+0x98/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:60
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f50aff9de99
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:00007f50b0f56028 EFLAGS: 00000246 ORIG_RAX: 000000000000003b
RAX: ffffffffffffffda RBX: 00007f50b0225fa0 RCX: 00007f50aff9de99
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000040
RBP: 00007f50b0033eaf R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f50b0226038 R14: 00007f50b0225fa0 R15: 00007ffd4c6fb838
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:mnt_add_count fs/namespace.c:179 [inline]
RIP: 0010:mntget+0x2e/0x60 fs/namespace.c:1296
Code: 41 56 53 48 89 fb e8 41 95 a9 ff 48 85 db 74 30 e8 37 95 a9 ff 4c 8d 73 50 4c 89 f0 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 74 08 4c 89 f7 e8 c4 1f ef ff 49 8b 06 65 ff 00 eb 05
RSP: 0018:ffffc9000e5b7400 EFLAGS: 00010206
RAX: 000000000000000a RBX: 0000000000000001 RCX: dffffc0000000000
RDX: ffffc90003a13000 RSI: 00000000000022dd RDI: 00000000000022de
RBP: ffffc9000e5b7410 R08: ffffc9000e5b74af R09: 1ffff92001cb6e95
R10: dffffc0000000000 R11: fffff52001cb6e96 R12: 0000000000000000
R13: ffffc9000e5b7401 R14: 0000000000000051 R15: ffffc9000e5b74a0
FS:  00007f50b0f566c0(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fca0c26e000 CR3: 000000013532d000 CR4: 00000000003526b0
----------------
Code disassembly (best guess):
   0:	41 56                	push   %r14
   2:	53                   	push   %rbx
   3:	48 89 fb             	mov    %rdi,%rbx
   6:	e8 41 95 a9 ff       	call   0xffa9954c
   b:	48 85 db             	test   %rbx,%rbx
   e:	74 30                	je     0x40
  10:	e8 37 95 a9 ff       	call   0xffa9954c
  15:	4c 8d 73 50          	lea    0x50(%rbx),%r14
  19:	4c 89 f0             	mov    %r14,%rax
  1c:	48 c1 e8 03          	shr    $0x3,%rax
  20:	48 b9 00 00 00 00 00 	movabs $0xdffffc0000000000,%rcx
  27:	fc ff df
* 2a:	80 3c 08 00          	cmpb   $0x0,(%rax,%rcx,1) <-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 f7             	mov    %r14,%rdi
  33:	e8 c4 1f ef ff       	call   0xffef1ffc
  38:	49 8b 06             	mov    (%r14),%rax
  3b:	65 ff 00             	incl   %gs:(%rax)
  3e:	eb 05                	jmp    0x45