gro: fix aggregation for skb using frag_list

[ Upstream commit 73d3fe6d1c6d840763ceafa9afae0aaafa18c4b5 ]

In commit 8a29111c7ca6 ("net: gro: allow to build full sized skb")
I added a regression for linear skb that traditionally force GRO
to use the frag_list fallback.

Erez Shitrit found that at most two segments were aggregated and
the "if (skb_gro_len(p) != pinfo->gso_size)" test was failing.

This is because pinfo at this spot still points to the last skb in the
chain, instead of the first one, where we find the correct gso_size
information.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Fixes: 8a29111c7ca6 ("net: gro: allow to build full sized skb")
Reported-by: Erez Shitrit <erezsh@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index da1351ecb146b2719be8932b29d64135ee05f574..baf6fc457df9bcbf05d4a25678e15c15ae963f0a 100644 (file)
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3140,6 +3140,9 @@ int skb_gro_receive(struct sk_buff **head, struct sk_buff *skb)
                NAPI_GRO_CB(skb)->free = NAPI_GRO_FREE_STOLEN_HEAD;
                goto done;
        }
+       /* switch back to head shinfo */
+       pinfo = skb_shinfo(p);
+
        if (pinfo->frag_list)
                goto merge;
        if (skb_gro_len(p) != pinfo->gso_size)