# Re: \[PATCH v4 2/3\] net: add kcov handle to skb extensions

- From: Willem de Bruijn \<willemdebruijn.kernel@gmail.com\>
- Date: 2020-10-28 21:49:02 
- List: netdev
- Page: https://ratatoskr.run/netdev/2020/10/6154749
- Thread: https://ratatoskr.run/netdev/2020/10/6155237/t.md

```text
On Wed, Oct 28, 2020 at 2:21 PM Aleksandr Nogikh
[ref] wrote:
>
> From: Aleksandr Nogikh <redacted>
>
> Remote KCOV coverage collection enables coverage-guided fuzzing of the
> code that is not reachable during normal system call execution. It is
> especially helpful for fuzzing networking subsystems, where it is
> common to perform packet handling in separate work queues even for the
> packets that originated directly from the user space.
>
> Enable coverage-guided frame injection by adding kcov remote handle to
> skb extensions. Default initialization in __alloc_skb and
> __build_skb_around ensures that no socket buffer that was generated
> during a system call will be missed.
>
> Code that is of interest and that performs packet processing should be
> annotated with kcov_remote_start()/kcov_remote_stop().
>
> An alternative approach is to determine kcov_handle solely on the
> basis of the device/interface that received the specific socket
> buffer. However, in this case it would be impossible to distinguish
> between packets that originated during normal background network
> processes or were intentionally injected from the user space.
>
> Signed-off-by: Aleksandr Nogikh <redacted>

Acked-by: Willem de Bruijn <willemb@google.com>
```