[Android 5.15] general protection fault in ovl_lookup_single

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 05eea940894a ANDROID: GKI: preserve the kernel API for str..
git tree: android13-5.15-lts
console output: https://syzkaller.appspot.com/x/log.txt?x=12bb8c2e580000
kernel config: https://syzkaller.appspot.com/x/.config?x=daefb08bb2811735
dashboard link: https://syzkaller.appspot.com/bug?extid=d9d0ec2cc95b5f9a408e
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14e09d96580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12756c2e580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e158e2d934a2/disk-05eea940.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/95d8715fb0e7/vmlinux-05eea940.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d046a12b451d/bzImage-05eea940.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+d9d0ec...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 PID: 374 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
RIP: 0010:ovl_lookup_positive_unlocked fs/overlayfs/namei.c:207 [inline]
RIP: 0010:ovl_lookup_single+0x89/0x870 fs/overlayfs/namei.c:230
Code: bd 1d b2 ff 48 89 c3 48 3d 01 f0 ff ff 72 0a e8 dd 8e 68 ff e9 de 03 00 00 49 89 dd 49 c1 ed 03 48 b8 00 00 00 00 00 fc ff df <41> 0f b6 44 05 00 84 c0 0f 85 ce 05 00 00 44 8b 23 44 89 e6 81 e6
RSP: 0018:ffffc90000b77a58 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000016 RCX: 8b5cd3dec39d5c00
RDX: 0000000000000001 RSI: 0000000000000008 RDI: 00000000ffffffff
RBP: ffffc90000b77a90 R08: ffff888111e0d2a7 R09: 1ffff110223c1a54
R10: dffffc0000000000 R11: ffffed10223c1a55 R12: ffff88810d1dd110
R13: 0000000000000002 R14: 0000000000000000 R15: ffffffff855e6e20
FS: 00007f26d58a76c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f26d5865d58 CR3: 000000012c4ba000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ovl_lookup_layer+0x355/0x420 fs/overlayfs/namei.c:314
ovl_lookup+0x6aa/0x1750 fs/overlayfs/namei.c:914
lookup_one_qstr_excl+0x114/0x250 fs/namei.c:1571
filename_create+0x235/0x470 fs/namei.c:3844
do_mkdirat+0x5c/0x4c0 fs/namei.c:4088
__do_sys_mkdirat fs/namei.c:4113 [inline]
__se_sys_mkdirat fs/namei.c:4111 [inline]
__x64_sys_mkdirat+0x89/0xa0 fs/namei.c:4111
x64_sys_call+0x37e/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:259
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: 0033:0x7f26d5a44e59
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:00007f26d58a7028 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f26d5cbdfa0 RCX: 00007f26d5a44e59
RDX: 0000000000000000 RSI: 0000200000002000 RDI: ffffffffffffff9c
RBP: 00007f26d5adad6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f26d5cbe038 R14: 00007f26d5cbdfa0 R15: 00007ffd3e91c1f8
</TASK>
Modules linked in:
---[ end trace e55cb5cbed593566 ]---
RIP: 0010:ovl_lookup_positive_unlocked fs/overlayfs/namei.c:207 [inline]
RIP: 0010:ovl_lookup_single+0x89/0x870 fs/overlayfs/namei.c:230
Code: bd 1d b2 ff 48 89 c3 48 3d 01 f0 ff ff 72 0a e8 dd 8e 68 ff e9 de 03 00 00 49 89 dd 49 c1 ed 03 48 b8 00 00 00 00 00 fc ff df <41> 0f b6 44 05 00 84 c0 0f 85 ce 05 00 00 44 8b 23 44 89 e6 81 e6
RSP: 0018:ffffc90000b77a58 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000016 RCX: 8b5cd3dec39d5c00
RDX: 0000000000000001 RSI: 0000000000000008 RDI: 00000000ffffffff
RBP: ffffc90000b77a90 R08: ffff888111e0d2a7 R09: 1ffff110223c1a54
R10: dffffc0000000000 R11: ffffed10223c1a55 R12: ffff88810d1dd110
R13: 0000000000000002 R14: 0000000000000000 R15: ffffffff855e6e20
FS: 00007f26d58a76c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f26d5a92540 CR3: 000000012c4ba000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: bd 1d b2 ff 48 mov $0x48ffb21d,%ebp
5: 89 c3 mov %eax,%ebx
7: 48 3d 01 f0 ff ff cmp $0xfffffffffffff001,%rax
d: 72 0a jb 0x19
f: e8 dd 8e 68 ff call 0xff688ef1
14: e9 de 03 00 00 jmp 0x3f7
19: 49 89 dd mov %rbx,%r13
1c: 49 c1 ed 03 shr $0x3,%r13
20: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
27: fc ff df
* 2a: 41 0f b6 44 05 00 movzbl 0x0(%r13,%rax,1),%eax <-- trapping instruction
30: 84 c0 test %al,%al
32: 0f 85 ce 05 00 00 jne 0x606
38: 44 8b 23 mov (%rbx),%r12d
3b: 44 89 e6 mov %r12d,%esi
3e: 81 .byte 0x81
3f: e6 .byte 0xe6


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