From f761312023a1f0d625e34daadd54c3f9cb2a4ac2 Mon Sep 17 00:00:00 2001 From: "Nikita V. Shirokov" Date: Wed, 25 Apr 2018 07:15:03 -0700 Subject: [PATCH] bpf: fix xdp_generic for bpf_adjust_tail usecase When bpf_adjust_tail was introduced for generic xdp, it changed skb's tail pointer, so it was pointing to the new "end of the packet". However skb's len field wasn't properly modified, so on the wire ethernet frame had original (or even bigger, if adjust_head was used) size. This diff is fixing this. Fixes: 198d83bb3 (" bpf: make generic xdp compatible w/ bpf_xdp_adjust_tail") Signed-off-by: Nikita V. Shirokov Signed-off-by: Daniel Borkmann --- net/core/dev.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/core/dev.c b/net/core/dev.c index c624a04..8f8931b 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -4057,8 +4057,10 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, * pckt. */ off = orig_data_end - xdp.data_end; - if (off != 0) + if (off != 0) { skb_set_tail_pointer(skb, xdp.data_end - xdp.data); + skb->len -= off; + } switch (act) { case XDP_REDIRECT: -- 2.7.4