Re: [syzbot] [kernel?] BUG: unable to handle kernel NULL pointer dereference in deactivate_slab

[Borislav Petkov]

+ linux-mm

syzbot folks: might wanna refresh your patterns on how this automated
thing is deciding who to Cc. This is clearly a mm issue.

On Mon, May 27, 2024 at 01:04:26AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    1613e604df0c Linux 6.10-rc1
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=15410752980000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=733cc7a95171d8e7
> dashboard link: https://syzkaller.appspot.com/bug?extid=79388700e25aa19555b9
> compiler:       gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: i386
> 
> Unfortunately, I don't have any reproducer for this issue yet.
> 
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-1613e604.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/bdfe02141e4c/vmlinux-1613e604.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/9e655c2629f1/bzImage-1613e604.xz
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+79388700e25aa19555b9@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> BUG: kernel NULL pointer dereference, address: 0000000000000001
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 256e3067 P4D 256e3067 PUD 4977c067 PMD 0 
> Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
> CPU: 3 PID: 56 Comm: kworker/3:1 Not tainted 6.10.0-rc1-syzkaller #0
> Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
> Workqueue: slub_flushwq flush_cpu_slab
> RIP: 0010:PagePoisoned include/linux/page-flags.h:296 [inline]
> RIP: 0010:page_to_nid include/linux/mm.h:1664 [inline]
> RIP: 0010:folio_nid include/linux/mm.h:1670 [inline]
> RIP: 0010:slab_nid mm/slab.h:194 [inline]
> RIP: 0010:deactivate_slab+0x1b/0x4a0 mm/slub.c:2880
> Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 56 49 89 f6 41 55 41 54 53 48 83 e4 f0 48 81 ec b0 00 00 00 <48> 8b 06 48 89 54 24 08 48 83 f8 ff 0f 84 c3 03 00 00 48 8b 06 48
> RSP: 0018:ffffc9000076fbb0 EFLAGS: 00010282
> RAX: 0000000000000002 RBX: ffffe8ffad339190 RCX: 1ffffffff28415f8
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff888021133540
> RBP: ffffc9000076fc88 R08: 0000000000000001 R09: fffffbfff283ee5e
> R10: ffffffff941f72f7 R11: ffffffff81e16fea R12: 0000000000000200
> R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000003
> FS:  0000000000000000(0000) GS:ffff88802c300000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000001 CR3: 000000001b47c000 CR4: 0000000000350ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  <TASK>
>  flush_slab mm/slub.c:3100 [inline]
>  flush_cpu_slab+0x141/0x410 mm/slub.c:3146
>  process_one_work+0x958/0x1ad0 kernel/workqueue.c:3231
>  process_scheduled_works kernel/workqueue.c:3312 [inline]
>  worker_thread+0x6c8/0xf70 kernel/workqueue.c:3393
>  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:
> CR2: 0000000000000001
> ---[ end trace 0000000000000000 ]---
> RIP: 0010:PagePoisoned include/linux/page-flags.h:296 [inline]
> RIP: 0010:page_to_nid include/linux/mm.h:1664 [inline]
> RIP: 0010:folio_nid include/linux/mm.h:1670 [inline]
> RIP: 0010:slab_nid mm/slab.h:194 [inline]
> RIP: 0010:deactivate_slab+0x1b/0x4a0 mm/slub.c:2880
> Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 55 48 89 e5 41 57 41 56 49 89 f6 41 55 41 54 53 48 83 e4 f0 48 81 ec b0 00 00 00 <48> 8b 06 48 89 54 24 08 48 83 f8 ff 0f 84 c3 03 00 00 48 8b 06 48
> RSP: 0018:ffffc9000076fbb0 EFLAGS: 00010282
> RAX: 0000000000000002 RBX: ffffe8ffad339190 RCX: 1ffffffff28415f8
> RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff888021133540
> RBP: ffffc9000076fc88 R08: 0000000000000001 R09: fffffbfff283ee5e
> R10: ffffffff941f72f7 R11: ffffffff81e16fea R12: 0000000000000200
> R13: 0000000000000001 R14: 0000000000000001 R15: 0000000000000003
> FS:  0000000000000000(0000) GS:ffff88802c300000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000001 CR3: 000000001b47c000 CR4: 0000000000350ef0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> ----------------
> Code disassembly (best guess):
>    0:	90                   	nop
>    1:	90                   	nop
>    2:	90                   	nop
>    3:	90                   	nop
>    4:	90                   	nop
>    5:	90                   	nop
>    6:	90                   	nop
>    7:	90                   	nop
>    8:	90                   	nop
>    9:	90                   	nop
>    a:	90                   	nop
>    b:	90                   	nop
>    c:	90                   	nop
>    d:	90                   	nop
>    e:	90                   	nop
>    f:	55                   	push   %rbp
>   10:	48 89 e5             	mov    %rsp,%rbp
>   13:	41 57                	push   %r15
>   15:	41 56                	push   %r14
>   17:	49 89 f6             	mov    %rsi,%r14
>   1a:	41 55                	push   %r13
>   1c:	41 54                	push   %r12
>   1e:	53                   	push   %rbx
>   1f:	48 83 e4 f0          	and    $0xfffffffffffffff0,%rsp
>   23:	48 81 ec b0 00 00 00 	sub    $0xb0,%rsp
> * 2a:	48 8b 06             	mov    (%rsi),%rax <-- trapping instruction
>   2d:	48 89 54 24 08       	mov    %rdx,0x8(%rsp)
>   32:	48 83 f8 ff          	cmp    $0xffffffffffffffff,%rax
>   36:	0f 84 c3 03 00 00    	je     0x3ff
>   3c:	48 8b 06             	mov    (%rsi),%rax
>   3f:	48                   	rex.W
> 
> 
> ---
> This report is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx.
> 
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> 
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> 
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> 
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> 
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-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette