Message-ID: <8bf5e24e-1bce-81dc-4e92-80ce20c5d152@iogearbox.net>
Date:   Sun, 14 Jan 2018 01:22:13 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Dmitry Vyukov <dvyukov@...gle.com>,
        syzbot <syzbot+32b24f3e7c9000c48490@...kaller.appspotmail.com>
Cc:     Alexei Starovoitov <ast@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>, syzkaller-bugs@...glegroups.com
Subject: Re: BUG: unable to handle kernel paging request in
 check_memory_region

On 01/13/2018 08:29 AM, Dmitry Vyukov wrote:
> On Fri, Jan 12, 2018 at 11:58 PM, syzbot
> <syzbot+32b24f3e7c9000c48490@...kaller.appspotmail.com> wrote:
>> Hello,
>>
>> syzkaller hit the following crash on
>> c92a9a461dff6140c539c61e457aa97df29517d6
>> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
>> compiler: gcc (GCC) 7.1.1 20170620
>> .config is attached
>> Raw console output is attached.
>> C reproducer is attached
>> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
>> for information about syzkaller reproducers
>>
>>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+32b24f3e7c9000c48490@...kaller.appspotmail.com
>> It will help syzbot understand when the bug is fixed. See footer for
>> details.
>> If you forward the report, please keep this part and the footer.
> 
> 
> Daniel, is it the same bug that was fixed by "bpf, array: fix overflow
> in max_entries and undefined behavior in index_mask"?

And also here, fixed by:

https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=bbeb6e4323dad9b5e0ee9f60c223dd532e2403b1

>> audit: type=1400 audit(1515790631.378:9): avc:  denied  { sys_chroot } for
>> pid=3510 comm="syzkaller602893" capability=18
>> scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023
>> tcontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023 tclass=cap_userns
>> permissive=1
>> BUG: unable to handle kernel paging request at ffffed004e875e33
>> IP: bytes_is_nonzero mm/kasan/kasan.c:166 [inline]
>> IP: memory_is_nonzero mm/kasan/kasan.c:184 [inline]
>> IP: memory_is_poisoned_n mm/kasan/kasan.c:210 [inline]
>> IP: memory_is_poisoned mm/kasan/kasan.c:241 [inline]
>> IP: check_memory_region_inline mm/kasan/kasan.c:257 [inline]
>> IP: check_memory_region+0x61/0x190 mm/kasan/kasan.c:267
>> PGD 21ffee067 P4D 21ffee067 PUD 21ffec067 PMD 0
>> Oops: 0000 [#1] SMP KASAN
>> Dumping ftrace buffer:
>>    (ftrace buffer empty)
>> Modules linked in:
>> CPU: 0 PID: 3510 Comm: syzkaller602893 Not tainted 4.15.0-rc7+ #259
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> RIP: 0010:bytes_is_nonzero mm/kasan/kasan.c:166 [inline]
>> RIP: 0010:memory_is_nonzero mm/kasan/kasan.c:184 [inline]
>> RIP: 0010:memory_is_poisoned_n mm/kasan/kasan.c:210 [inline]
>> RIP: 0010:memory_is_poisoned mm/kasan/kasan.c:241 [inline]
>> RIP: 0010:check_memory_region_inline mm/kasan/kasan.c:257 [inline]
>> RIP: 0010:check_memory_region+0x61/0x190 mm/kasan/kasan.c:267
>> RSP: 0018:ffff8801bfa77770 EFLAGS: 00010202
>> RAX: ffffed004e875e33 RBX: ffff8802743af19b RCX: ffffffff817deb1c
>> RDX: 0000000000000000 RSI: 0000000000000004 RDI: ffff8802743af198
>> RBP: ffff8801bfa77780 R08: 1ffff1004e875e33 R09: ffffed004e875e33
>> R10: 0000000000000001 R11: ffffed004e875e33 R12: ffffed004e875e34
>> R13: ffff8802743af198 R14: ffff8801bfc9f000 R15: ffff8801c135a680
>> FS:  0000000001a1d880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000
>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>> CR2: ffffed004e875e33 CR3: 00000001bfe22003 CR4: 00000000001606f0
>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
>> Call Trace:
>>  memcpy+0x23/0x50 mm/kasan/kasan.c:302
>>  memcpy include/linux/string.h:344 [inline]
>>  map_lookup_elem+0x4dc/0xbd0 kernel/bpf/syscall.c:584
>>  SYSC_bpf kernel/bpf/syscall.c:1711 [inline]
>>  SyS_bpf+0x922/0x4400 kernel/bpf/syscall.c:1685
>>  entry_SYSCALL_64_fastpath+0x23/0x9a
>> RIP: 0033:0x440ac9
>> RSP: 002b:00000000007dff68 EFLAGS: 00000203 ORIG_RAX: 0000000000000141
>> RAX: ffffffffffffffda RBX: ffffffffffffffff RCX: 0000000000440ac9
>> RDX: 0000000000000018 RSI: 0000000020eed000 RDI: 0000000000000001
>> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000203 R12: 00000000004022a0
>> R13: 0000000000402330 R14: 0000000000000000 R15: 0000000000000000
>> Code: 89 f8 49 c1 e8 03 49 89 db 49 c1 eb 03 4d 01 cb 4d 01 c1 4d 8d 63 01
>> 4c 89 c8 4d 89 e2 4d 29 ca 49 83 fa 10 7f 3d 4d 85 d2 74 33 <41> 80 39 00 75
>> 21 48 b8 01 00 00 00 00 fc ff df 4d 01 d1 49 01
>> RIP: bytes_is_nonzero mm/kasan/kasan.c:166 [inline] RSP: ffff8801bfa77770
>> RIP: memory_is_nonzero mm/kasan/kasan.c:184 [inline] RSP: ffff8801bfa77770
>> RIP: memory_is_poisoned_n mm/kasan/kasan.c:210 [inline] RSP:
>> ffff8801bfa77770
>> RIP: memory_is_poisoned mm/kasan/kasan.c:241 [inline] RSP: ffff8801bfa77770
>> RIP: check_memory_region_inline mm/kasan/kasan.c:257 [inline] RSP:
>> ffff8801bfa77770
>> RIP: check_memory_region+0x61/0x190 mm/kasan/kasan.c:267 RSP:
>> ffff8801bfa77770
>> CR2: ffffed004e875e33
>> ---[ end trace 769bd3705f3abe78 ]---
>> Kernel panic - not syncing: Fatal exception
>> Dumping ftrace buffer:
>>    (ftrace buffer empty)
>> Kernel Offset: disabled
>> Rebooting in 86400 seconds..
>>
>>
>> ---
>> This bug is generated by a dumb bot. It may contain errors.
>> See https://goo.gl/tpsmEJ for details.
>> Direct all questions to syzkaller@...glegroups.com.
>>
>> syzbot will keep track of this bug report.
>> If you forgot to add the Reported-by tag, once the fix for this bug is
>> merged
>> into any tree, please reply to this email with:
>> #syz fix: exact-commit-title
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