Re: WARNING: kmalloc bug in xdp_umem_create

[Dmitry Vyukov]

On Sun, Jun 10, 2018 at 11:31 AM, BjÃrn TÃpel <bjorn.topel@xxxxxxxxx> wrote:
> Den sÃn 10 juni 2018 kl 04:53 skrev Tetsuo Handa
> <penguin-kernel@xxxxxxxxxxxxxxxxxxx>:
>>
>> On 2018/06/10 7:47, syzbot wrote:
>> > Hello,
>> >
>> > syzbot found the following crash on:
>> >
>> > HEAD commit:    7d3bf613e99a Merge tag 'libnvdimm-for-4.18' of git://git.k..
>> > git tree:       upstream
>> > console output: https://syzkaller.appspot.com/x/log.txt?x=1073f68f800000
>> > kernel config:  https://syzkaller.appspot.com/x/.config?x=f04d8d0a2afb789a
>> > dashboard link: https://syzkaller.appspot.com/bug?extid=4abadc5d69117b346506
>> > compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>> > syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=13c9756f800000
>> > C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16366f9f800000
>> >
>> > IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> > Reported-by: syzbot+4abadc5d69117b346506@xxxxxxxxxxxxxxxxxxxxxxxxx
>> >
>> > 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)
>> > random: sshd: uninitialized urandom read (32 bytes read)
>> > WARNING: CPU: 1 PID: 4537 at mm/slab_common.c:996 kmalloc_slab+0x56/0x70 mm/slab_common.c:996
>> > Kernel panic - not syncing: panic_on_warn set ...
>>
>> syzbot gave up upon kmalloc(), but actually error handling path has
>> NULL pointer dereference bug.
>>
>
> Thanks Tetsuo! This crash has been fixed by Daniel Borkmann in commit
> c09290c56376 ("bpf, xdp: fix crash in xdp_umem_unaccount_pages").

Let's tell syzbot about this:

#syz fix: bpf, xdp: fix crash in xdp_umem_unaccount_pages