kernel BUG at mm/slab.c:LINE! (2)

kernel BUG at mm/slab.c:LINE! (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    d90c936fb318 Merge branch 'bpf-nfp-mul-div-support'
git tree:       bpf-next
console output: https://syzkaller.appspot.com/x/log.txt?x=15cf4f48400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a501a01deaf0fe9
dashboard link: https://syzkaller.appspot.com/bug?extid=885bda95271928dc24eb
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=15c87748400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1459050c400000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+885bda95271928dc24eb@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
------------[ cut here ]------------
kernel BUG at mm/slab.c:4421!
invalid opcode: 0000 [#1] SMP KASAN
CPU: 0 PID: 4467 Comm: syz-executor607 Not tainted 4.18.0-rc3+ #48
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
RIP: 0010:__check_heap_object+0xa7/0xb5 mm/slab.c:4446
Code: 48 c7 c7 90 73 c0 88 e8 87 7a 08 00 5d c3 41 8b 91 04 01 00 00 48 29  
c7 48 39 d7 77 be 48 01 d0 48 29 c8 48 39 f0 72 b3 5d c3 <0f> 0b 48 c7 c7  
90 73 c0 88 e8 6d 81 08 00 44 89 e1 4c 8d 45 c4 48
RSP: 0018:ffff8801ab117a10 EFLAGS: 00010246
RAX: 0000000000000006 RBX: 1ffff10035622f49 RCX: 0000000000000009
RDX: ffff8801c27ff000 RSI: 00000000000003d2 RDI: ffff8801c27ffff2
RBP: ffff8801ab117a10 R08: ffff8801ab37a680 R09: ffff8801da800940
R10: 0000000000000991 R11: 0000000000000001 R12: ffff8801c27ffff2
R13: 00000000000003d2 R14: 0000000000000001 R15: ffffea000709ffc0
FS:  0000000000763880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000200 CR3: 00000001b0a8b000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
  check_heap_object mm/usercopy.c:236 [inline]
  __check_object_size+0x4db/0x5f2 mm/usercopy.c:259
  check_object_size include/linux/thread_info.h:119 [inline]
  check_copy_size include/linux/thread_info.h:150 [inline]
  copy_to_user include/linux/uaccess.h:154 [inline]
  bpf_test_finish.isra.7+0xd9/0x1f0 net/bpf/test_run.c:59
  bpf_prog_test_run_skb+0x7d7/0xa30 net/bpf/test_run.c:144
  bpf_prog_test_run+0x130/0x1a0 kernel/bpf/syscall.c:1686
  __do_sys_bpf kernel/bpf/syscall.c:2323 [inline]
  __se_sys_bpf kernel/bpf/syscall.c:2267 [inline]
  __x64_sys_bpf+0x3d8/0x510 kernel/bpf/syscall.c:2267
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4402d9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 0f 83 fb 13 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fff168c6558 EFLAGS: 00000213 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 00000000004402d9
RDX: 0000000000000028 RSI: 0000000020000080 RDI: 000000000000000a
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 0000000000000000 R11: 0000000000000213 R12: 0000000000401b60
R13: 0000000000401bf0 R14: 0000000000000000 R15: 0000000000000000
Modules linked in:
Dumping ftrace buffer:
    (ftrace buffer empty)
---[ end trace 045402f983996608 ]---
RIP: 0010:__check_heap_object+0xa7/0xb5 mm/slab.c:4446
Code: 48 c7 c7 90 73 c0 88 e8 87 7a 08 00 5d c3 41 8b 91 04 01 00 00 48 29  
c7 48 39 d7 77 be 48 01 d0 48 29 c8 48 39 f0 72 b3 5d c3 <0f> 0b 48 c7 c7  
90 73 c0 88 e8 6d 81 08 00 44 89 e1 4c 8d 45 c4 48
RSP: 0018:ffff8801ab117a10 EFLAGS: 00010246
RAX: 0000000000000006 RBX: 1ffff10035622f49 RCX: 0000000000000009
RDX: ffff8801c27ff000 RSI: 00000000000003d2 RDI: ffff8801c27ffff2
RBP: ffff8801ab117a10 R08: ffff8801ab37a680 R09: ffff8801da800940
R10: 0000000000000991 R11: 0000000000000001 R12: ffff8801c27ffff2
R13: 00000000000003d2 R14: 0000000000000001 R15: ffffea000709ffc0
FS:  0000000000763880(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020000200 CR3: 00000001b0a8b000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400


---
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Re: kernel BUG at mm/slab.c:LINE! (2)

[Christopher Lameter]

On Sun, 8 Jul 2018, syzbot wrote:

> kernel BUG at mm/slab.c:4421!

Classic location that indicates memory corruption. Can we rerun this with
CONFIG_SLAB_DEBUG? Alternatively use SLUB debugging for better debugging
without rebuilding.

Re: kernel BUG at mm/slab.c:LINE! (2)

[Dmitry Vyukov]

On Mon, Jul 9, 2018 at 6:05 PM, Christopher Lameter <cl@linux.com> wrote:
> On Sun, 8 Jul 2018, syzbot wrote:
>
>> kernel BUG at mm/slab.c:4421!
>
> Classic location that indicates memory corruption. Can we rerun this with
> CONFIG_SLAB_DEBUG? Alternatively use SLUB debugging for better debugging
> without rebuilding.

This runs with KASAN which is way more powerful than slab/slub debug.

There two other recent crashes in bpf_test_finish which has more info:

https://syzkaller.appspot.com/bug?id=f831c88feddf5f4de09b846bbe53e5b8c06e5c02
https://syzkaller.appspot.com/bug?id=059cee5623ce519359e7440ba6d0d6af8b82694e

Re: kernel BUG at mm/slab.c:LINE! (2)

[Daniel Borkmann]

On 07/09/2018 06:16 PM, Dmitry Vyukov wrote:
> On Mon, Jul 9, 2018 at 6:05 PM, Christopher Lameter <cl@linux.com> wrote:
>> On Sun, 8 Jul 2018, syzbot wrote:
>>
>>> kernel BUG at mm/slab.c:4421!
>>
>> Classic location that indicates memory corruption. Can we rerun this with
>> CONFIG_SLAB_DEBUG? Alternatively use SLUB debugging for better debugging
>> without rebuilding.
> 
> This runs with KASAN which is way more powerful than slab/slub debug.
> 
> There two other recent crashes in bpf_test_finish which has more info:
> 
> https://syzkaller.appspot.com/bug?id=f831c88feddf5f4de09b846bbe53e5b8c06e5c02
> https://syzkaller.appspot.com/bug?id=059cee5623ce519359e7440ba6d0d6af8b82694e

Fyi, looking into the two today as well.