syzbot

general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 0 PID: 5875 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:traverse_mounts fs/namei.c:1443 [inline]
RIP: 0010:handle_mounts fs/namei.c:1555 [inline]
RIP: 0010:step_into+0x129/0xf20 fs/namei.c:1848
Code: 74 24 08 c6 44 24 7f 00 43 0f b6 04 3c 84 c0 4d 89 fd 0f 85 fd 0b 00 00 45 8b 36 4c 8b bc 24 a8 00 00 00 4c 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 fc 0b 00 00 45 8b 3f 44 89 fe 81 e6 00
RSP: 0018:ffffc90003057ac0 EFLAGS: 00010206
RAX: 0000000000000003 RBX: ffffc90003057ca0 RCX: ffff888027113c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003057bc8 R08: ffff88805dc5ded7 R09: 1ffff1100bb8bbda
R10: dffffc0000000000 R11: ffffed100bb8bbdb R12: 1ffff9200060af9b
R13: dffffc0000000000 R14: 0000000000000080 R15: 0000000000000018
FS:  0000555570e5b500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555570e86aa8 CR3: 000000002f2ba000 CR4: 00000000003506f0
Call Trace:
 <TASK>
 lookup_last fs/namei.c:2467 [inline]
 path_lookupat+0x169/0x440 fs/namei.c:2491
 filename_lookup+0x228/0x560 fs/namei.c:2520
 user_path_at_empty+0x42/0x60 fs/namei.c:2917
 user_path_at include/linux/namei.h:57 [inline]
 ksys_umount fs/namespace.c:1921 [inline]
 __do_sys_umount fs/namespace.c:1929 [inline]
 __se_sys_umount fs/namespace.c:1927 [inline]
 __x64_sys_umount+0xfd/0x180 fs/namespace.c:1927
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fb1df39da57
Code: a2 c7 05 9c fc 24 00 00 00 00 00 eb 96 e8 e1 12 00 00 90 31 f6 e9 09 00 00 00 66 0f 1f 84 00 00 00 00 00 b8 a6 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8
RSP: 002b:00007ffcb192ba28 EFLAGS: 00000246 ORIG_RAX: 00000000000000a6
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fb1df39da57
RDX: 0000000000000000 RSI: 0000000000000009 RDI: 00007ffcb192bae0
RBP: 00007ffcb192bae0 R08: 00007ffcb192cae0 R09: 00000000ffffffff
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffcb192cbd0
R13: 00007fb1df432048 R14: 0000555570e5b4e8 R15: 00007ffcb192ed90
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:traverse_mounts fs/namei.c:1443 [inline]
RIP: 0010:handle_mounts fs/namei.c:1555 [inline]
RIP: 0010:step_into+0x129/0xf20 fs/namei.c:1848
Code: 74 24 08 c6 44 24 7f 00 43 0f b6 04 3c 84 c0 4d 89 fd 0f 85 fd 0b 00 00 45 8b 36 4c 8b bc 24 a8 00 00 00 4c 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 fc 0b 00 00 45 8b 3f 44 89 fe 81 e6 00
RSP: 0018:ffffc90003057ac0 EFLAGS: 00010206
RAX: 0000000000000003 RBX: ffffc90003057ca0 RCX: ffff888027113c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90003057bc8 R08: ffff88805dc5ded7 R09: 1ffff1100bb8bbda
R10: dffffc0000000000 R11: ffffed100bb8bbdb R12: 1ffff9200060af9b
R13: dffffc0000000000 R14: 0000000000000080 R15: 0000000000000018
FS:  0000555570e5b500(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f05eada1796 CR3: 000000002f2ba000 CR4: 00000000003506f0
----------------
Code disassembly (best guess):
   0:	74 24                	je     0x26
   2:	08 c6                	or     %al,%dh
   4:	44 24 7f             	rex.R and $0x7f,%al
   7:	00 43 0f             	add    %al,0xf(%rbx)
   a:	b6 04                	mov    $0x4,%dh
   c:	3c 84                	cmp    $0x84,%al
   e:	c0 4d 89 fd          	rorb   $0xfd,-0x77(%rbp)
  12:	0f 85 fd 0b 00 00    	jne    0xc15
  18:	45 8b 36             	mov    (%r14),%r14d
  1b:	4c 8b bc 24 a8 00 00 	mov    0xa8(%rsp),%r15
  22:	00
  23:	4c 89 f8             	mov    %r15,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 fc 0b 00 00    	jne    0xc33
  37:	45 8b 3f             	mov    (%r15),%r15d
  3a:	44 89 fe             	mov    %r15d,%esi
  3d:	81                   	.byte 0x81
  3e:	e6 00                	out    %al,$0x0