syzbot

loop0: detected capacity change from 0 to 128
EXT4-fs (loop0): mounted filesystem 76b65be2-f6da-4727-8c75-0525a5b65a09 r/w without journal. Quota mode: none.
ext4 filesystem being mounted at /0/mnt supports timestamps until 2038-01-19 (0x7fffffff)
general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 1 PID: 5942 Comm: syz.0.16 Not tainted 6.6.100-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:utf8nlookup+0x39/0xa50 fs/unicode/utf8-norm.c:306
Code: 89 44 24 10 49 89 ce 48 89 14 24 89 f5 49 89 fd 49 bf 00 00 00 00 00 fc ff df e8 f2 36 f8 fe 49 8d 5d 18 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 d8 7c 4f ff 48 8b 1b 48 83 c3 30
RSP: 0018:ffffc900033074a0 EFLAGS: 00010206
RAX: 0000000000000003 RBX: 0000000000000018 RCX: ffff88802700da00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: ffffc90003307638 R11: fffff52000660eca R12: dffffc0000000000
R13: 0000000000000000 R14: ffff888073789ae0 R15: dffffc0000000000
FS:  0000555568dcf500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fe3309ff000 CR3: 00000000771b5000 CR4: 00000000003506e0
Call Trace:
 <TASK>
 utf8byte+0x34f/0x1370 fs/unicode/utf8-norm.c:-1
 utf8_casefold+0x130/0x230 fs/unicode/utf8-core.c:109
 ext4_fname_setup_ci_filename+0x1d5/0x430 fs/ext4/namei.c:1463
 ext4_fname_prepare_lookup+0x213/0x3a0 fs/ext4/crypto.c:55
 ext4_lookup_entry fs/ext4/namei.c:1767 [inline]
 ext4_lookup+0xfa/0x6d0 fs/ext4/namei.c:1842
 lookup_open fs/namei.c:3466 [inline]
 open_last_lookups fs/namei.c:3556 [inline]
 path_openat+0x10b8/0x3190 fs/namei.c:3786
 do_filp_open+0x1c5/0x3d0 fs/namei.c:3816
 do_sys_openat2+0x12c/0x1c0 fs/open.c:1419
 do_sys_open fs/open.c:1434 [inline]
 __do_sys_openat fs/open.c:1450 [inline]
 __se_sys_openat fs/open.c:1445 [inline]
 __x64_sys_openat+0x139/0x160 fs/open.c:1445
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe339d8e9a9
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:00007ffe99dc2948 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fe339fb5fa0 RCX: 00007fe339d8e9a9
RDX: 0000000000008042 RSI: 00002000000000c0 RDI: ffffffffffffff9c
RBP: 00007fe339e10d69 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000108 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe339fb5fa0 R14: 00007fe339fb5fa0 R15: 0000000000000004
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:utf8nlookup+0x39/0xa50 fs/unicode/utf8-norm.c:306
Code: 89 44 24 10 49 89 ce 48 89 14 24 89 f5 49 89 fd 49 bf 00 00 00 00 00 fc ff df e8 f2 36 f8 fe 49 8d 5d 18 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 d8 7c 4f ff 48 8b 1b 48 83 c3 30
RSP: 0018:ffffc900033074a0 EFLAGS: 00010206
RAX: 0000000000000003 RBX: 0000000000000018 RCX: ffff88802700da00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000
RBP: 0000000000000001 R08: 0000000000000005 R09: 0000000000000000
R10: ffffc90003307638 R11: fffff52000660eca R12: dffffc0000000000
R13: 0000000000000000 R14: ffff888073789ae0 R15: dffffc0000000000
FS:  0000555568dcf500(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fd3d9696000 CR3: 00000000771b5000 CR4: 00000000003506e0
----------------
Code disassembly (best guess):
   0:	89 44 24 10          	mov    %eax,0x10(%rsp)
   4:	49 89 ce             	mov    %rcx,%r14
   7:	48 89 14 24          	mov    %rdx,(%rsp)
   b:	89 f5                	mov    %esi,%ebp
   d:	49 89 fd             	mov    %rdi,%r13
  10:	49 bf 00 00 00 00 00 	movabs $0xdffffc0000000000,%r15
  17:	fc ff df
  1a:	e8 f2 36 f8 fe       	call   0xfef83711
  1f:	49 8d 5d 18          	lea    0x18(%r13),%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 d8 7c 4f ff       	call   0xff4f7d11
  39:	48 8b 1b             	mov    (%rbx),%rbx
  3c:	48 83 c3 30          	add    $0x30,%rbx