From f761312023a1f0d625e34daadd54c3f9cb2a4ac2 Mon Sep 17 00:00:00 2001
From: "Nikita V. Shirokov" <tehnerd@tehnerd.com>
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 <tehnerd@tehnerd.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
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:
--
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