netdev - Re: [PATCH bpf] bpf: fix bpf_skb_load_bytes

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Message-ID: <CAADnVQ+rhWLbyprt7+J6FSVk29BX0-dNG38qUpw49ikmvmcBZg@mail.gmail.com>
Date:   Sun, 29 Jul 2018 18:41:08 +0300
From:   Alexei Starovoitov <alexei.starovoitov@...il.com>
To:     Daniel Borkmann <daniel@...earbox.net>
Cc:     Network Development <netdev@...r.kernel.org>,
        Martin KaFai Lau <kafai@...com>
Subject: Re: [PATCH bpf] bpf: fix bpf_skb_load_bytes_relative pkt length check

On Sat, Jul 28, 2018 at 10:04 PM, Daniel Borkmann <daniel@...earbox.net> wrote:
> The len > skb_headlen(skb) cannot be used as a maximum upper bound
> for the packet length since it does not have any relation to the full
> linear packet length when filtering is used from upper layers (e.g.
> in case of reuseport BPF programs) as by then skb->data, skb->len
> already got mangled through __skb_pull() and others.
>
> Fixes: 4e1ec56cdc59 ("bpf: add skb_load_bytes_relative helper")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Acked-by: Martin KaFai Lau <kafai@...com>

Great catch.
Acked-by: Alexei Starovoitov <ast@...nel.org>