From 06660e972c10b06fb77cedef73a6c061f9c3b68f 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: b8341ea72 (" 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 c624a04dad1fb..8f8931b93140e 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: -- 2.39.5