[syzbot] [fs?] general protection fault in do_getname_kernel

[syzbot <syzbot+2f6a3b7dc3b442ef515c@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    848acc8ffe1b Merge tag 'fsverity-for-linus' of git://git.k..
git tree:       upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13154bb9580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=cb17729fb04b1e3a
dashboard link: https://syzkaller.appspot.com/bug?extid=2f6a3b7dc3b442ef515c
compiler:       Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=169bacc6580000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1305fc9e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/375d27e96ecb/disk-848acc8f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4ba19a656b9d/vmlinux-848acc8f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7c2a17aaee7c/bzImage-848acc8f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2f6a3b7dc3b442ef515c@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 5608 Comm: syz-executor162 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:strlen+0x29/0x70 lib/string.c:402
Code: 90 f3 0f 1e fa 41 57 41 56 41 54 53 48 c7 c0 ff ff ff ff 49 be 00 00 00 00 00 fc ff df 48 89 fb 49 89 c7 48 89 d8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 75 11 48 ff c3 49 8d 47 01 42 80 7c 3f 01 00
RSP: 0018:ffffc900043ef978 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88803cd4dd00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900043efab8 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f5f467 R12: 1ffff9200087df40
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffffffffffffffff
FS:  0000555563612400(0000) GS:ffff888125d3e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563591bce000 CR3: 0000000046a98000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 __fortify_strlen include/linux/fortify-string.h:218 [inline]
 do_getname_kernel+0x1d/0x230 fs/namei.c:260
 class_filename_kernel_constructor include/linux/fs.h:2565 [inline]
 filp_open+0x87/0x1d0 fs/open.c:1342
 nvmet_file_ns_enable+0x74/0x360 drivers/nvme/target/io-cmd-file.c:41
 nvmet_ns_enable+0xaa/0x780 drivers/nvme/target/core.c:596
 nvmet_ns_enable_store+0xd7/0x170 drivers/nvme/target/configfs.c:735
 flush_write_buffer fs/configfs/file.c:207 [inline]
 configfs_write_iter+0x33a/0x430 fs/configfs/file.c:229
 new_sync_write fs/read_write.c:595 [inline]
 vfs_write+0x61e/0xbb0 fs/read_write.c:687
 ksys_write+0x156/0x270 fs/read_write.c:739
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb41977f689
Code: c0 79 93 eb d5 48 8d 7c 1d 00 eb 99 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 d8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe221a7f98 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000200000000000 RCX: 00007fb41977f689
RDX: 0000000000000001 RSI: 0000200000000580 RDI: 0000000000000004
RBP: 6769666e6f632f2e R08: 0000000000000006 R09: 0000000000000006
R10: 0000000000000006 R11: 0000000000000246 R12: 00007ffe221a8108
R13: 0000200000000008 R14: 00007fb419812c40 R15: 0000000000000002
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:strlen+0x29/0x70 lib/string.c:402
Code: 90 f3 0f 1e fa 41 57 41 56 41 54 53 48 c7 c0 ff ff ff ff 49 be 00 00 00 00 00 fc ff df 48 89 fb 49 89 c7 48 89 d8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 75 11 48 ff c3 49 8d 47 01 42 80 7c 3f 01 00
RSP: 0018:ffffc900043ef978 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffff88803cd4dd00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900043efab8 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f5f467 R12: 1ffff9200087df40
R13: dffffc0000000000 R14: dffffc0000000000 R15: ffffffffffffffff
FS:  0000555563612400(0000) GS:ffff888125d3e000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000563591bce000 CR3: 0000000046a98000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
   0:	90                   	nop
   1:	f3 0f 1e fa          	endbr64
   5:	41 57                	push   %r15
   7:	41 56                	push   %r14
   9:	41 54                	push   %r12
   b:	53                   	push   %rbx
   c:	48 c7 c0 ff ff ff ff 	mov    $0xffffffffffffffff,%rax
  13:	49 be 00 00 00 00 00 	movabs $0xdffffc0000000000,%r14
  1a:	fc ff df
  1d:	48 89 fb             	mov    %rdi,%rbx
  20:	49 89 c7             	mov    %rax,%r15
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 30       	movzbl (%rax,%r14,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	75 11                	jne    0x44
  33:	48 ff c3             	inc    %rbx
  36:	49 8d 47 01          	lea    0x1(%r15),%rax
  3a:	42 80 7c 3f 01 00    	cmpb   $0x0,0x1(%rdi,%r15,1)


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