ipv6: fix incorrent ipv6 ipsec packet fragment

Since commit 299b0767(ipv6: Fix IPsec slowpath fragmentation problem)
In func ip6_append_data,after call skb_put(skb, fraglen + dst_exthdrlen)
the skb->len contains dst_exthdrlen,and we don't reduce dst_exthdrlen at last
This will make fraggap>0 in next "while cycle",and cause the size of skb incorrent

Fix this by reserve headroom for dst_exthdrlen.

Signed-off-by: Gao feng <gaofeng@cn.fujitsu.com>
Acked-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 5 deletions

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 7a98fc2a5d97..b7ca46161cb9 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -1414,8 +1414,9 @@ alloc_new_skb:
                          */
                         skb->ip_summed = csummode;
                         skb->csum = 0;
-                        /* reserve for fragmentation */
-                        skb_reserve(skb, hh_len+sizeof(struct frag_hdr));
+                        /* reserve for fragmentation and ipsec header */
+                        skb_reserve(skb, hh_len + sizeof(struct frag_hdr) +
+                                    dst_exthdrlen);
 
                         if (sk->sk_type == SOCK_DGRAM)
                                 skb_shinfo(skb)->tx_flags = tx_flags;
@@ -1423,9 +1424,9 @@ alloc_new_skb:
                         /*
                          *      Find where to start putting bytes
                          */
-                        data = skb_put(skb, fraglen + dst_exthdrlen);
-                        skb_set_network_header(skb, exthdrlen + dst_exthdrlen);
-                        data += fragheaderlen + dst_exthdrlen;
+                        data = skb_put(skb, fraglen);
+                        skb_set_network_header(skb, exthdrlen);
+                        data += fragheaderlen;
                         skb->transport_header = (skb->network_header +
                                                  fragheaderlen);
                         if (fraggap) {