From: Daniel Borkmann <[email protected]>
Date: Tue, 6 Jun 2017 18:38:04 +0200
> Commit fb9a307d11d6 ("bpf: Allow CGROUP_SKB eBPF program to
> access sk_buff") enabled programs of BPF_PROG_TYPE_CGROUP_SKB
> type to use ld_abs/ind instructions. However, at this point,
> we cannot use them, since offsets relative to SKF_LL_OFF will
> end up pointing skb_mac_header(skb) out of bounds since in the
> egress path it is not yet set at that point in time, but only
> after __dev_queue_xmit() did a general reset on the mac header.
> bpf_internal_load_pointer_neg_helper() will then end up reading
> data from a wrong offset.
>
> BPF_PROG_TYPE_CGROUP_SKB programs can use bpf_skb_load_bytes()
> already to access packet data, which is also more flexible than
> the insns carried over from cBPF.
>
> Fixes: fb9a307d11d6 ("bpf: Allow CGROUP_SKB eBPF program to access sk_buff")
> Signed-off-by: Daniel Borkmann <[email protected]>
> Acked-by: Alexei Starovoitov <[email protected]>
Aha, I see, applied.
Thanks!
