linux-kernel - Re: [syzbot] [mm?] general protection fault in do_migrate

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <a299097b-7070-44c4-97ec-40dcf87c5c21@redhat.com>
Date: Wed, 20 Nov 2024 17:39:43 +0100
From: David Hildenbrand <david@...hat.com>
To: syzbot <syzbot+3511625422f7aa637f0d@...kaller.appspotmail.com>,
 akpm@...ux-foundation.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [mm?] general protection fault in do_migrate_pages

On 20.11.24 16:38, David Hildenbrand wrote:
> On 20.11.24 01:00, syzbot wrote:
>> Hello,
>>
>> syzbot found the following issue on:
>>
>> HEAD commit:    f868cd251776 Merge tag 'drm-fixes-2024-11-16' of https://g..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=15473cc0580000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=ff8e8187a30080b5
>> dashboard link: https://syzkaller.appspot.com/bug?extid=3511625422f7aa637f0d
>> 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=17e8d130580000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=159c71a7980000
>>
>> Downloadable assets:
>> disk image: https://storage.googleapis.com/syzbot-assets/a0d46da55993/disk-f868cd25.raw.xz
>> vmlinux: https://storage.googleapis.com/syzbot-assets/da57ef4813fd/vmlinux-f868cd25.xz
>> kernel image: https://storage.googleapis.com/syzbot-assets/3cdde892ea08/bzImage-f868cd25.xz
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+3511625422f7aa637f0d@...kaller.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: 1 UID: 0 PID: 6021 Comm: syz-executor284 Not tainted 6.12.0-rc7-syzkaller-00187-gf868cd251776 #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
>> RIP: 0010:migrate_to_node mm/mempolicy.c:1090 [inline]
>> RIP: 0010:do_migrate_pages+0x403/0x6f0 mm/mempolicy.c:1194
>> Code: 8b 54 24 30 41 83 c8 10 80 3a 00 4d 63 c0 0f 85 d1 02 00 00 48 89 c1 48 8b 54 24 18 48 be 00 00 00 00 00 fc ff df 48 c1 e9 03 <80> 3c 31 00 48 8b 92 b0 00 00 00 0f 85 74 02 00 00 48 8b 30 49 89
>> RSP: 0018:ffffc9000375fd08 EFLAGS: 00010246
>> RAX: 0000000000000000 RBX: ffffc9000375fd78 RCX: 0000000000000000
>> RDX: ffff88807e171300 RSI: dffffc0000000000 RDI: ffff88803390c044
>> RBP: ffff88807e171428 R08: 0000000000000014 R09: fffffbfff2039ef1
>> R10: ffffffff901cf78f R11: 0000000000000000 R12: 0000000000000003
>> R13: ffffc9000375fe90 R14: ffffc9000375fe98 R15: ffffc9000375fdf8
>> FS:  00005555919e1380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00005555919e1ca8 CR3: 000000007f12a000 CR4: 00000000003526f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>    <TASK>
>>    kernel_migrate_pages+0x5b2/0x750 mm/mempolicy.c:1709
>>    __do_sys_migrate_pages mm/mempolicy.c:1727 [inline]
>>    __se_sys_migrate_pages mm/mempolicy.c:1723 [inline]
>>    __x64_sys_migrate_pages+0x96/0x100 mm/mempolicy.c:1723
>>    do_syscall_x64 arch/x86/entry/common.c:52 [inline]
>>    do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
>>    entry_SYSCALL_64_after_hwframe+0x77/0x7f
>> RIP: 0033:0x7fedcca74af9
>> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
>> RSP: 002b:00007ffe4d85c278 EFLAGS: 00000206 ORIG_RAX: 0000000000000100
>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fedcca74af9
>> RDX: 0000000020000000 RSI: 000000000000005a RDI: 0000000000001786
>> RBP: 0000000000010bf2 R08: 0000000000006080 R09: 0000000000000006
>> R10: 0000000020000040 R11: 0000000000000206 R12: 00007ffe4d85c28c
>> R13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001
>>    </TASK>
>> Modules linked in:
>> ---[ end trace 0000000000000000 ]---
>> RIP: 0010:migrate_to_node mm/mempolicy.c:1090 [inline]
>> RIP: 0010:do_migrate_pages+0x403/0x6f0 mm/mempolicy.c:1194
>> Code: 8b 54 24 30 41 83 c8 10 80 3a 00 4d 63 c0 0f 85 d1 02 00 00 48 89 c1 48 8b 54 24 18 48 be 00 00 00 00 00 fc ff df 48 c1 e9 03 <80> 3c 31 00 48 8b 92 b0 00 00 00 0f 85 74 02 00 00 48 8b 30 49 89
>> RSP: 0018:ffffc9000375fd08 EFLAGS: 00010246
>> RAX: 0000000000000000 RBX: ffffc9000375fd78 RCX: 0000000000000000
>> RDX: ffff88807e171300 RSI: dffffc0000000000 RDI: ffff88803390c044
>> RBP: ffff88807e171428 R08: 0000000000000014 R09: fffffbfff2039ef1
>> R10: ffffffff901cf78f R11: 0000000000000000 R12: 0000000000000003
>> R13: ffffc9000375fe90 R14: ffffc9000375fe98 R15: ffffc9000375fdf8
>> FS:  00005555919e1380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00005555919e1ca8 CR3: 000000007f12a000 CR4: 00000000003526f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> ----------------
>> Code disassembly (best guess):
>>      0:	8b 54 24 30          	mov    0x30(%rsp),%edx
>>      4:	41 83 c8 10          	or     $0x10,%r8d
>>      8:	80 3a 00             	cmpb   $0x0,(%rdx)
>>      b:	4d 63 c0             	movslq %r8d,%r8
>>      e:	0f 85 d1 02 00 00    	jne    0x2e5
>>     14:	48 89 c1             	mov    %rax,%rcx
>>     17:	48 8b 54 24 18       	mov    0x18(%rsp),%rdx
>>     1c:	48 be 00 00 00 00 00 	movabs $0xdffffc0000000000,%rsi
>>     23:	fc ff df
>>     26:	48 c1 e9 03          	shr    $0x3,%rcx
>> * 2a:	80 3c 31 00          	cmpb   $0x0,(%rcx,%rsi,1) <-- trapping instruction
>>     2e:	48 8b 92 b0 00 00 00 	mov    0xb0(%rdx),%rdx
>>     35:	0f 85 74 02 00 00    	jne    0x2af
>>     3b:	48 8b 30             	mov    (%rax),%rsi
>>     3e:	49                   	rex.WB
>>     3f:	89                   	.byte 0x89
>>
> 
> Hmmm, there is not much meat in this report :)
> 
> The reproducer seems to execute migrate_pages() in a fork'ed child
> process, and kills that process after a while. Not 100% sure if the
> concurrent killing of the process is relevant.
> 
> Before the child process calls migrate_pages(), it executes
> MADV_DONTFORK on the complete address space (funny, I wonder what that
> does ...) and then calls clone3() without CLONE_VM.
> 

After running it for a while in a VM with the given config:

[  827.514143][T37171] Oops: general protection fault, probably for 
non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN NOPTI
[  827.516614][T37171] KASAN: null-ptr-deref in range 
[0x0000000000000000-0x0000000000000007]
[  827.518162][T37171] CPU: 4 UID: 0 PID: 37171 Comm: repro4 Not tainted 
6.12.0-rc7-00187-gf868cd251776 #99
[  827.519935][T37171] Hardware name: QEMU Standard PC (Q35 + ICH9, 
2009), BIOS 1.16.3-2.fc40 04/01/2014
[  827.521648][T37171] RIP: 0010:do_migrate_pages+0x404/0x6e0
[  827.522774][T37171] Code: 10 80 39 00 4d 63 c0 0f 85 9b 02 00 00 48 
be 00 00 00 00 00 fc ff df 48 8b 4c 24 28 48 8b 91 b0 00 00 00 48 89 c1 
48 c1 e9 03 <80> 3c 31 00 0f 85 95 02 00 00 48 8b 30 49 89 d9 48 8b 4c 
24 08 48
[  827.526342][T37171] RSP: 0018:ffffc90028157ce8 EFLAGS: 00010256
[  827.527480][T37171] RAX: 0000000000000000 RBX: ffffc90028157d68 RCX: 
0000000000000000
[  827.528942][T37171] RDX: 00007ffffffff000 RSI: dffffc0000000000 RDI: 
ffff88811dcd8444
[  827.530406][T37171] RBP: 0000000000000003 R08: 0000000000000014 R09: 
ffff88811dcd8ad8
[  827.531865][T37171] R10: ffffffff903e668f R11: 0000000000000000 R12: 
ffffc90028157e80
[  827.533341][T37171] R13: ffff8881f3a2b0a8 R14: ffffc90028157e28 R15: 
ffffc90028157e88
[  827.534806][T37171] FS:  00007f096d49f740(0000) 
GS:ffff8881f4a00000(0000) knlGS:0000000000000000
[  827.536452][T37171] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  827.537672][T37171] CR2: 00007ff2dcb96810 CR3: 00000001eed18000 CR4: 
0000000000750ef0
[  827.539135][T37171] PKRU: 55555554
[  827.539799][T37171] Call Trace:
[  827.540407][T37171]  <TASK>
[  827.540965][T37171]  ? die_addr.cold+0x8/0xd
[  827.541823][T37171]  ? exc_general_protection+0x147/0x240
[  827.542888][T37171]  ? asm_exc_general_protection+0x26/0x30
[  827.543960][T37171]  ? do_migrate_pages+0x404/0x6e0
[  827.544915][T37171]  ? do_migrate_pages+0x3cd/0x6e0
[  827.545873][T37171]  ? __pfx_do_migrate_pages+0x10/0x10
[  827.546895][T37171]  ? do_raw_spin_lock+0x12a/0x2b0
[  827.547854][T37171]  ? apparmor_capable+0x11c/0x3b0
[  827.548818][T37171]  ? srso_alias_return_thunk+0x5/0xfbef5
[  827.549878][T37171]  ? srso_alias_return_thunk+0x5/0xfbef5
[  827.550937][T37171]  ? security_capable+0x80/0x260
[  827.551893][T37171]  kernel_migrate_pages+0x5b7/0x750
[  827.552891][T37171]  ? __pfx_kernel_migrate_pages+0x10/0x10
[  827.553975][T37171]  ? srso_alias_return_thunk+0x5/0xfbef5
[  827.555028][T37171]  ? rcu_is_watching+0x12/0xc0
[  827.555938][T37171]  ? srso_alias_return_thunk+0x5/0xfbef5
[  827.557000][T37171]  __x64_sys_migrate_pages+0x96/0x100
[  827.558022][T37171]  ? srso_alias_return_thunk+0x5/0xfbef5
[  827.559077][T37171]  ? lockdep_hardirqs_on+0x7b/0x110
[  827.560052][T37171]  do_syscall_64+0xc7/0x250
[  827.560909][T37171]  entry_SYSCALL_64_after_hwframe+0x77/0x7f


-- 
Cheers,

David / dhildenb