[v5.15] general protection fault in security_inode_getattr (4)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: cc5ec8769306 Linux 5.15.196
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17599c92580000
kernel config: https://syzkaller.appspot.com/x/.config?x=e1bb6d24ef2164eb
dashboard link: https://syzkaller.appspot.com/bug?extid=2a14542d7a6ac3681efd
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c71c660545b2/disk-cc5ec876.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4f011826cca6/vmlinux-cc5ec876.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8ccd1a2c3f8c/bzImage-cc5ec876.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2a1454...@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: 8870 Comm: syz.8.881 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:d_backing_inode include/linux/dcache.h:553 [inline]
RIP: 0010:security_inode_getattr+0x42/0x120 security/security.c:1346
Code: de fd 4c 8d 73 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 ac 16 23 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 8f 16 23 fe 4d 8b 36 49 83 c6 0c
RSP: 0018:ffffc9000305f968 EFLAGS: 00010202
RAX: 000000000000000d RBX: ffffc9000305fa80 RCX: 0000000000080000
RDX: ffffc90016400000 RSI: 00000000000008aa RDI: 00000000000008ab
RBP: ffffc9000305fc90 R08: dffffc0000000000 R09: ffffc9000305fb70
R10: 0000000000000000 R11: 0000000000000010 R12: dffffc0000000000
R13: ffffc9000305fb70 R14: 0000000000000068 R15: ffffc9000305fa80
FS: 00007f1ef70686c0(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1ef7067f98 CR3: 0000000060a1b000 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_getattr+0x338/0xdf0 fs/overlayfs/inode.c:245
vfs_statx+0x149/0x4d0 fs/stat.c:225
vfs_fstatat fs/stat.c:243 [inline]
__do_sys_newfstatat fs/stat.c:411 [inline]
__se_sys_newfstatat fs/stat.c:405 [inline]
__x64_sys_newfstatat+0x12c/0x1b0 fs/stat.c:405
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: 0033:0x7f1ef8e21fc9
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:00007f1ef7068038 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 00007f1ef9079090 RCX: 00007f1ef8e21fc9
RDX: 0000000000000000 RSI: 0000200000000340 RDI: ffffffffffffff9c
RBP: 00007f1ef8ea4f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000800 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1ef9079128 R14: 00007f1ef9079090 R15: 00007fffe4cd4058
</TASK>
Modules linked in:
---[ end trace 5c8fd693ebcb021d ]---
RIP: 0010:d_backing_inode include/linux/dcache.h:553 [inline]
RIP: 0010:security_inode_getattr+0x42/0x120 security/security.c:1346
Code: de fd 4c 8d 73 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 ac 16 23 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 8f 16 23 fe 4d 8b 36 49 83 c6 0c
RSP: 0018:ffffc9000305f968 EFLAGS: 00010202
RAX: 000000000000000d RBX: ffffc9000305fa80 RCX: 0000000000080000
RDX: ffffc90016400000 RSI: 00000000000008aa RDI: 00000000000008ab
RBP: ffffc9000305fc90 R08: dffffc0000000000 R09: ffffc9000305fb70
R10: 0000000000000000 R11: 0000000000000010 R12: dffffc0000000000
R13: ffffc9000305fb70 R14: 0000000000000068 R15: ffffc9000305fa80
FS: 00007f1ef70686c0(0000) GS:ffff8880b9100000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555c151cf950 CR3: 0000000060a1b000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: de fd fdivrp %st,%st(5)
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 ac 16 23 fe call 0xfe2316c8
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 8f 16 23 fe call 0xfe2316c8
39: 4d 8b 36 mov (%r14),%r14
3c: 49 83 c6 0c add $0xc,%r14


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