linux-kernel - Re: [PATCH v4 2/3] net: add kcov handle to skb extensions

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Date:   Wed, 28 Oct 2020 16:42:45 -0400
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Aleksandr Nogikh <aleksandrnogikh@...il.com>
Cc:     David Miller <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Johannes Berg <johannes@...solutions.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Marco Elver <elver@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        linux-wireless <linux-wireless@...r.kernel.org>,
        Aleksandr Nogikh <nogikh@...gle.com>
Subject: Re: [PATCH v4 2/3] net: add kcov handle to skb extensions

On Wed, Oct 28, 2020 at 2:21 PM Aleksandr Nogikh
<aleksandrnogikh@...il.com> wrote:
>
> From: Aleksandr Nogikh <nogikh@...gle.com>
>
> 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 <nogikh@...gle.com>

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