netdev - Re: [PATCH net-next] bpf: restore skb->sk before pskb

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Date:   Wed, 26 Apr 2017 18:14:51 +0200
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Eric Dumazet <eric.dumazet@...il.com>,
        David Miller <davem@...emloft.net>
CC:     netdev <netdev@...r.kernel.org>,
        Andrey Konovalov <andreyknvl@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH net-next] bpf: restore skb->sk before pskb_trim() call

On 04/26/2017 06:09 PM, Eric Dumazet wrote:
> From: Eric Dumazet <edumazet@...gle.com>
>
> While testing a fix [1] in ___pskb_trim(), addressing the WARN_ON_ONCE()
> in skb_try_coalesce() reported by Andrey, I found that we had an skb
> with skb->sk set but no skb->destructor.
>
> This invalidated heuristic found in commit 158f323b9868 ("net: adjust
> skb->truesize in pskb_expand_head()") and in cited patch.
>
> Considering the BUG_ON(skb->sk) we have in skb_orphan(), we should
> restrain the temporary setting to a minimal section.
>
> [1] https://patchwork.ozlabs.org/patch/755570/
>      net: adjust skb->truesize in ___pskb_trim()
>
> Fixes: 8f917bba0042 ("bpf: pass sk to helper functions")
> Signed-off-by: Eric Dumazet <edumazet@...gle.com>
> Cc: Willem de Bruijn <willemb@...gle.com>
> Cc: Andrey Konovalov <andreyknvl@...gle.com>

Good point, thanks!

Acked-by: Daniel Borkmann <daniel@...earbox.net>