[syzbot] [tomoyo?] general protection fault in tomoyo_gc_thread

[syzbot <syzbot+bf6351831bc4f9148d98@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    f92f4749861b Merge tag 'clk-fixes-for-linus' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12fa2cdf980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=99a5586995ec03b2
dashboard link: https://syzkaller.appspot.com/bug?extid=bf6351831bc4f9148d98
compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12fc78f8580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b85403132ddc/disk-f92f4749.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/20613d034287/vmlinux-f92f4749.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d1ea80bf7e4e/bzImage-f92f4749.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+bf6351831bc4f9148d98@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 UID: 0 PID: 6044 Comm: GC for TOMOYO Not tainted 6.13.0-rc2-syzkaller-00031-gf92f4749861b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
RIP: 0010:tomoyo_collect_acl security/tomoyo/gc.c:511 [inline]
RIP: 0010:tomoyo_collect_entry security/tomoyo/gc.c:537 [inline]
RIP: 0010:tomoyo_gc_thread security/tomoyo/gc.c:619 [inline]
RIP: 0010:tomoyo_gc_thread+0x1ab/0x1390 security/tomoyo/gc.c:612
Code: 3b 5c 47 fd c6 45 18 ff 4c 89 ee bf 09 00 00 00 e8 8a f1 ff ff e8 25 5c 47 fd 48 89 d8 48 89 de 49 89 dd 48 c1 e8 03 83 e6 07 <42> 0f b6 0c 20 48 8d 43 07 48 89 c2 48 c1 ea 03 42 0f b6 14 22 40
RSP: 0018:ffffc90003367e78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8451e1ab
RDX: ffff888074e85a00 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff888143b02f00 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000b8f R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888025b49b00
FS:  0000000000000000(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000008 CR3: 0000000028642000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kthread+0x2c1/0x3a0 kernel/kthread.c:389
 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:tomoyo_collect_acl security/tomoyo/gc.c:511 [inline]
RIP: 0010:tomoyo_collect_entry security/tomoyo/gc.c:537 [inline]
RIP: 0010:tomoyo_gc_thread security/tomoyo/gc.c:619 [inline]
RIP: 0010:tomoyo_gc_thread+0x1ab/0x1390 security/tomoyo/gc.c:612
Code: 3b 5c 47 fd c6 45 18 ff 4c 89 ee bf 09 00 00 00 e8 8a f1 ff ff e8 25 5c 47 fd 48 89 d8 48 89 de 49 89 dd 48 c1 e8 03 83 e6 07 <42> 0f b6 0c 20 48 8d 43 07 48 89 c2 48 c1 ea 03 42 0f b6 14 22 40
RSP: 0018:ffffc90003367e78 EFLAGS: 00010246
RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8451e1ab
RDX: ffff888074e85a00 RSI: 0000000000000000 RDI: 0000000000000001
RBP: ffff888143b02f00 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000b8f R12: dffffc0000000000
R13: 0000000000000000 R14: 0000000000000000 R15: ffff888025b49b00
FS:  0000000000000000(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055b9c4865950 CR3: 0000000029aee000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	3b 5c 47 fd          	cmp    -0x3(%rdi,%rax,2),%ebx
   4:	c6 45 18 ff          	movb   $0xff,0x18(%rbp)
   8:	4c 89 ee             	mov    %r13,%rsi
   b:	bf 09 00 00 00       	mov    $0x9,%edi
  10:	e8 8a f1 ff ff       	call   0xfffff19f
  15:	e8 25 5c 47 fd       	call   0xfd475c3f
  1a:	48 89 d8             	mov    %rbx,%rax
  1d:	48 89 de             	mov    %rbx,%rsi
  20:	49 89 dd             	mov    %rbx,%r13
  23:	48 c1 e8 03          	shr    $0x3,%rax
  27:	83 e6 07             	and    $0x7,%esi
* 2a:	42 0f b6 0c 20       	movzbl (%rax,%r12,1),%ecx <-- trapping instruction
  2f:	48 8d 43 07          	lea    0x7(%rbx),%rax
  33:	48 89 c2             	mov    %rax,%rdx
  36:	48 c1 ea 03          	shr    $0x3,%rdx
  3a:	42 0f b6 14 22       	movzbl (%rdx,%r12,1),%edx
  3f:	40                   	rex


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