[v5.15] general protection fault in security_inode_getattr (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3330a8d33e08 Linux 5.15.201
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17c64202580000
kernel config: https://syzkaller.appspot.com/x/.config?x=353ae28c40b35af5
dashboard link: https://syzkaller.appspot.com/bug?extid=04c6c46f7c990507d89a
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b65fe19af112/disk-3330a8d3.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/351948519a0d/vmlinux-3330a8d3.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a3b3f8477595/bzImage-3330a8d3.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+04c6c4...@syzkaller.appspotmail.com

general protection fault, probably for non-canonical address 0xdffffc000000000d: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000068-0x000000000000006f]
CPU: 0 PID: 4959 Comm: syz.2.238 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:d_backing_inode include/linux/dcache.h:553 [inline]
RIP: 0010:security_inode_getattr+0x42/0x120 security/security.c:1346
Code: d7 fd 4c 8d 73 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 bc fb 1c fe 4d 8b 36 49 83 c6 68 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 9f fb 1c fe 4d 8b 36 49 83 c6 0c
RSP: 0018:ffffc900030df308 EFLAGS: 00010202
RAX: 000000000000000d RBX: ffffc900030df690 RCX: 0000000000080000
RDX: ffffc9000edaa000 RSI: 000000000000618e RDI: 000000000000618f
RBP: ffffc900030df898 R08: ffffc900030df69f R09: ffffc900030df690
R10: dffffc0000000000 R11: fffff5200061bed4 R12: dffffc0000000000
R13: ffffc900030df6a0 R14: 0000000000000068 R15: ffffc900030df690
FS: 00007f0635d406c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b3281bff8 CR3: 0000000024746000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
vfs_getattr+0x26/0x3a0 fs/stat.c:157
ovl_copy_up_one fs/overlayfs/copy_up.c:965 [inline]
ovl_copy_up_flags+0x44e/0x1eb0 fs/overlayfs/copy_up.c:1051
ovl_maybe_copy_up+0x14f/0x180 fs/overlayfs/copy_up.c:1083
ovl_open+0x9b/0x1f0 fs/overlayfs/file.c:149
do_dentry_open+0x7ff/0xf80 fs/open.c:826
do_open fs/namei.c:3616 [inline]
path_openat+0x26f5/0x2fa0 fs/namei.c:3750
do_filp_open+0x1e2/0x410 fs/namei.c:3777
file_open_name+0x15f/0x1b0 fs/open.c:1200
acct_on kernel/acct.c:216 [inline]
__do_sys_acct kernel/acct.c:309 [inline]
__se_sys_acct+0x10f/0x7b0 kernel/acct.c:296
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: 0033:0x7f0637b07629
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:00007f0635d40028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a3
RAX: ffffffffffffffda RBX: 00007f0637d81090 RCX: 00007f0637b07629
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000140
RBP: 00007f0637b9db39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f0637d81128 R14: 00007f0637d81090 R15: 00007fff02410c88
</TASK>
Modules linked in:
---[ end trace 1f4c11867452081d ]---
RIP: 0010:d_backing_inode include/linux/dcache.h:553 [inline]
RIP: 0010:security_inode_getattr+0x42/0x120 security/security.c:1346
Code: d7 fd 4c 8d 73 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 bc fb 1c fe 4d 8b 36 49 83 c6 68 4c 89 f0 48 c1 e8 03 <42> 80 3c 20 00 74 08 4c 89 f7 e8 9f fb 1c fe 4d 8b 36 49 83 c6 0c
RSP: 0018:ffffc900030df308 EFLAGS: 00010202
RAX: 000000000000000d RBX: ffffc900030df690 RCX: 0000000000080000
RDX: ffffc9000edaa000 RSI: 000000000000618e RDI: 000000000000618f
RBP: ffffc900030df898 R08: ffffc900030df69f R09: ffffc900030df690
R10: dffffc0000000000 R11: fffff5200061bed4 R12: dffffc0000000000
R13: ffffc900030df6a0 R14: 0000000000000068 R15: ffffc900030df690
FS: 00007f0635d406c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b32811ff8 CR3: 0000000024746000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: d7 xlat %ds:(%rbx)
1: fd std
2: 4c 8d 73 08 lea 0x8(%rbx),%r14
6: 4c 89 f0 mov %r14,%rax
9: 48 c1 e8 03 shr $0x3,%rax
d: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
12: 74 08 je 0x1c
14: 4c 89 f7 mov %r14,%rdi
17: e8 bc fb 1c fe call 0xfe1cfbd8
1c: 4d 8b 36 mov (%r14),%r14
1f: 49 83 c6 68 add $0x68,%r14
23: 4c 89 f0 mov %r14,%rax
26: 48 c1 e8 03 shr $0x3,%rax
* 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2f: 74 08 je 0x39
31: 4c 89 f7 mov %r14,%rdi
34: e8 9f fb 1c fe call 0xfe1cfbd8
39: 4d 8b 36 mov (%r14),%r14
3c: 49 83 c6 0c add $0xc,%r14


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