Re: net/tcp: warning in tcp_try_coalesce/skb_try_coalesce

[Eric Dumazet]

On Wed, Apr 26, 2017 at 5:08 AM, Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote:
> On Tue, Jan 31, 2017 at 2:17 PM, Andrey Konovalov <andreyknvl@xxxxxxxxxx> wrote:
>> Hi,
>>
>> I've got the following error report while running the syzkaller fuzzer.
>>
>> On commit 566cf877a1fcb6d6dc0126b076aad062054c2637 (4.10-rc6).
>>
>> The fuzzer hits this issue quite often, but I don't have a working reproducer.
>
> I still see this on 5a7ad1146caa895ad718a534399e38bd2ba721b7 (4.11-rc8).
>
> I also have a reproducer now, attached.
>
> It takes around 10 seconds for the warning to trigger.
>

It does not trigger for me, but seeing that you use SO_ATTACH_FILTER,
I have a pretty good idea how to remove this splat.

A call to skb_condense() from ___pskb_trim() will likely help, I will
post a patch after my commute.

Thanks.