[v6.1] general protection fault in security_inode_getattr (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8e6e2188d949 Linux 6.1.157
git tree: linux-6.1.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1490af34580000
kernel config: https://syzkaller.appspot.com/x/.config?x=7eb38bd5021fec61
dashboard link: https://syzkaller.appspot.com/bug?extid=08678ec09a9c42fd0e89
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/dcc01324de1b/disk-8e6e2188.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a93dd5469c70/vmlinux-8e6e2188.xz
kernel image: https://storage.googleapis.com/syzbot-assets/04635e384401/bzImage-8e6e2188.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+08678e...@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: 1 PID: 14584 Comm: syz.6.2036 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:543 [inline]
RIP: 0010:security_inode_getattr+0x42/0x120 security/security.c:1359
Code: be fd 4c 8d 73 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 fc 5b 0e 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 df 5b 0e fe 4d 8b 36 49 83 c6 0c
RSP: 0018:ffffc9000652f968 EFLAGS: 00010202
RAX: 000000000000000d RBX: ffffc9000652fa60 RCX: 0000000000080000
RDX: ffffc9001da03000 RSI: 0000000000000791 RDI: 0000000000000792
RBP: ffffc9000652fc90 R08: dffffc0000000000 R09: ffffc9000652fb60
R10: 0000000000000000 R11: 0000000000000008 R12: dffffc0000000000
R13: ffffc9000652fb60 R14: 0000000000000068 R15: ffffc9000652fa60
FS: 00007f09cd9e36c0(0000) GS:ffff8880b8f00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f09cd9e2f98 CR3: 0000000026749000 CR4: 00000000003506e0
DR0: 000000000000007f DR1: 000000000000f96f DR2: 0000000000000000
DR3: 0000000080000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
vfs_getattr+0x26/0x3a0 fs/stat.c:158
ovl_getattr+0x34c/0xe60 fs/overlayfs/inode.c:246
vfs_statx+0x16e/0x650 fs/stat.c:233
vfs_fstatat fs/stat.c:267 [inline]
__do_sys_newfstatat fs/stat.c:437 [inline]
__se_sys_newfstatat fs/stat.c:431 [inline]
__x64_sys_newfstatat+0x155/0x1e0 fs/stat.c:431
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f09ccb8efc9
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:00007f09cd9e3038 EFLAGS: 00000246 ORIG_RAX: 0000000000000106
RAX: ffffffffffffffda RBX: 00007f09ccde6090 RCX: 00007f09ccb8efc9
RDX: 0000200000000880 RSI: 0000200000000840 RDI: ffffffffffffff9c
RBP: 00007f09ccc11f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000800 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f09ccde6128 R14: 00007f09ccde6090 R15: 00007ffd1d265db8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:d_backing_inode include/linux/dcache.h:543 [inline]
RIP: 0010:security_inode_getattr+0x42/0x120 security/security.c:1359
Code: be fd 4c 8d 73 08 4c 89 f0 48 c1 e8 03 42 80 3c 20 00 74 08 4c 89 f7 e8 fc 5b 0e 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 df 5b 0e fe 4d 8b 36 49 83 c6 0c
RSP: 0018:ffffc9000652f968 EFLAGS: 00010202
RAX: 000000000000000d RBX: ffffc9000652fa60 RCX: 0000000000080000
RDX: ffffc9001da03000 RSI: 0000000000000791 RDI: 0000000000000792
RBP: ffffc9000652fc90 R08: dffffc0000000000 R09: ffffc9000652fb60
R10: 0000000000000000 R11: 0000000000000008 R12: dffffc0000000000
R13: ffffc9000652fb60 R14: 0000000000000068 R15: ffffc9000652fa60
FS: 00007f09cd9e36c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005640f6ecf410 CR3: 0000000026749000 CR4: 00000000003506f0
DR0: 000000000000007f DR1: 000000000000f96f DR2: 0000000000000000
DR3: 0000000080000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: be fd 4c 8d 73 mov $0x738d4cfd,%esi
5: 08 4c 89 f0 or %cl,-0x10(%rcx,%rcx,4)
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 fc 5b 0e fe call 0xfe0e5c18
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 df 5b 0e fe call 0xfe0e5c18
39: 4d 8b 36 mov (%r14),%r14
3c: 49 83 c6 0c add $0xc,%r14


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