Re: general protection fault in __aa_lookupn_ns

[Dmitry Vyukov]

On Fri, Sep 28, 2018 at 10:40 AM, Dmitry Vyukov <dvyukov@xxxxxxxxxx> wrote:
> On Wed, Sep 26, 2018 at 9:52 AM, syzbot
> <syzbot+9b37e75e781b5e400f65@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>> Hello,
>>
>> syzbot found the following crash on:
>>
>> HEAD commit:    dad486875956 Add linux-next specific files for 20180924
>> git tree:       linux-next
>> console output: https://syzkaller.appspot.com/x/log.txt?x=15da1fd1400000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=3e793f6258a2ee8f
>> dashboard link: https://syzkaller.appspot.com/bug?extid=9b37e75e781b5e400f65
>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=142c6769400000
>> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12af5556400000
>
> This is the same as "KASAN: stack-out-of-bounds Read in __aa_lookupn_ns":
> https://syzkaller.appspot.com/bug?id=f0d603856d8b3cc9b8e09228f2f548c18ef907ac
> right?


#syz dup: KASAN: stack-out-of-bounds Read in __aa_lookupn_ns

>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+9b37e75e781b5e400f65@xxxxxxxxxxxxxxxxxxxxxxxxx
>>
>> audit: type=1400 audit(1537815185.042:10): apparmor="DENIED"
>> operation="stack_onexec" info="label not found" error=-2
>> profile="unconfined" name="&&" pid=5560 comm="syz-executor398"
>> audit: type=1400 audit(1537815185.072:11): apparmor="DENIED"
>> operation="stack_onexec" info="label not found" error=-2
>> profile="unconfined" name="&&" pid=5561 comm="syz-executor398"
>> kasan: CONFIG_KASAN_INLINE enabled
>> kasan: GPF could be caused by NULL-ptr deref or user memory access
>> general protection fault: 0000 [#1] PREEMPT SMP KASAN
>> CPU: 0 PID: 5565 Comm: syz-executor398 Not tainted 4.19.0-rc5-next-20180924+
>> #78
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> RIP: 0010:memcmp+0x28/0x160 lib/string.c:856
>> Code: 00 00 48 85 d2 0f 84 0a 01 00 00 48 b8 00 00 00 00 00 fc ff df 55 48
>> 89 f9 48 89 e5 48 c1 e9 03 41 54 53 48 89 fb 48 83 ec 18 <0f> b6 04 01 48 89
>> f9 83 e1 07 38 c8 7f 08 84 c0 0f 85 98 00 00 00
>> RSP: 0018:ffff8801bbf0ef98 EFLAGS: 00010292
>> RAX: dffffc0000000000 RBX: 0000000041b58ab3 RCX: 000000000836b156
>> RDX: 0000000000000002 RSI: ffffffff885fb8e0 RDI: 0000000041b58ab3
>> RBP: ffff8801bbf0efc0 R08: ffff8801d8628280 R09: ffffed003b585b57
>> R10: ffffed003b585b57 R11: ffff8801dac2dabb R12: 0000000000000002
>> R13: ffffffff885fb8e0 R14: ffff8801fda67e03 R15: dffffc0000000000
>> FS:  0000000000bf8880(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00000000006cb090 CR3: 00000001d884a000 CR4: 00000000001406f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>  strnstr+0x4b/0x70 lib/string.c:934
>>  __aa_lookupn_ns+0xc1/0x570 security/apparmor/policy_ns.c:209
>>  aa_lookupn_ns+0x88/0x1e0 security/apparmor/policy_ns.c:240
>>  aa_fqlookupn_profile+0x1b9/0x1010 security/apparmor/policy.c:468
>>  fqlookupn_profile+0x80/0xc0 security/apparmor/label.c:1844
>>  aa_label_strn_parse+0xa3a/0x1230 security/apparmor/label.c:1908
>>  aa_label_parse+0x42/0x50 security/apparmor/label.c:1943
>>  aa_change_profile+0x513/0x3510 security/apparmor/domain.c:1362
>>  apparmor_setprocattr+0xab7/0x1180 security/apparmor/lsm.c:759
>>  security_setprocattr+0x66/0xc0 security/security.c:1336
>>  proc_pid_attr_write+0x301/0x540 fs/proc/base.c:2555
>>  __vfs_write+0x119/0x9f0 fs/read_write.c:485
>>  vfs_write+0x1fc/0x560 fs/read_write.c:549
>>  ksys_write+0x101/0x260 fs/read_write.c:598
>>  __do_sys_write fs/read_write.c:610 [inline]
>>  __se_sys_write fs/read_write.c:607 [inline]
>>  __x64_sys_write+0x73/0xb0 fs/read_write.c:607
>>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>> RIP: 0033:0x440d49
>> Code: e8 cc ab 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 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 bb 0a fc ff c3 66 2e 0f 1f 84 00 00 00 00
>> RSP: 002b:00007ffcbaaf0448 EFLAGS: 00000213 ORIG_RAX: 0000000000000001
>> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 0000000000440d49
>> RDX: 0000000000000009 RSI: 0000000020000180 RDI: 0000000000000003
>> RBP: 0000000000000000 R08: 00000000004002c8 R09: 00000000004002c8
>> R10: 0000000000bf8880 R11: 0000000000000213 R12: 0000000000008f07
>> R13: 0000000000401d20 R14: 0000000000000000 R15: 0000000000000000
>> Modules linked in:
>> ---[ end trace 848eed09df759209 ]---
>> RIP: 0010:memcmp+0x28/0x160 lib/string.c:856
>> Code: 00 00 48 85 d2 0f 84 0a 01 00 00 48 b8 00 00 00 00 00 fc ff df 55 48
>> 89 f9 48 89 e5 48 c1 e9 03 41 54 53 48 89 fb 48 83 ec 18 <0f> b6 04 01 48 89
>> f9 83 e1 07 38 c8 7f 08 84 c0 0f 85 98 00 00 00
>> RSP: 0018:ffff8801bbf0ef98 EFLAGS: 00010292
>> RAX: dffffc0000000000 RBX: 0000000041b58ab3 RCX: 000000000836b156
>> RDX: 0000000000000002 RSI: ffffffff885fb8e0 RDI: 0000000041b58ab3
>> RBP: ffff8801bbf0efc0 R08: ffff8801d8628280 R09: ffffed003b585b57
>> R10: ffffed003b585b57 R11: ffff8801dac2dabb R12: 0000000000000002
>> R13: ffffffff885fb8e0 R14: ffff8801fda67e03 R15: dffffc0000000000
>> FS:  0000000000bf8880(0000) GS:ffff8801dac00000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: 00000000006cb090 CR3: 00000001d884a000 CR4: 00000000001406f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>>
>>
>> ---
>> This bug 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@xxxxxxxxxxxxxxxxx
>>
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>> syzbot.
>> syzbot can test patches for this bug, for details see:
>> https://goo.gl/tpsmEJ#testing-patches