[PATCH 3/7] esp: Fix skb tailroom calculation

[Steffen Klassert]

We use skb_availroom to calculate the skb tailroom for the
ESP trailer. skb_availroom calculates the tailroom and
subtracts this value by reserved_tailroom. However
reserved_tailroom is a union with the skb mark. This means
that we subtract the tailroom by the skb mark if set.
Fix this by using skb_tailroom instead.

Fixes: cac2661c53f3 ("esp4: Avoid skb_cow_data whenever possible")
Fixes: 03e2a30f6a27 ("esp6: Avoid skb_cow_data whenever possible")
Signed-off-by: Steffen Klassert <steffen.klass...@secunet.com>
---
 net/ipv4/esp4.c | 2 +-
 net/ipv6/esp6.c | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/ipv4/esp4.c b/net/ipv4/esp4.c
index a8ddb95..df68963 100644
--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -258,7 +258,7 @@ int esp_output_head(struct xfrm_state *x, struct sk_buff 
*skb, struct esp_info *
                esp_output_udp_encap(x, skb, esp);
 
        if (!skb_cloned(skb)) {
-               if (tailen <= skb_availroom(skb)) {
+               if (tailen <= skb_tailroom(skb)) {
                        nfrags = 1;
                        trailer = skb;
                        tail = skb_tail_pointer(trailer);
diff --git a/net/ipv6/esp6.c b/net/ipv6/esp6.c
index 4e3fdc88..ab64f36 100644
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -226,7 +226,7 @@ int esp6_output_head(struct xfrm_state *x, struct sk_buff 
*skb, struct esp_info
        int tailen = esp->tailen;
 
        if (!skb_cloned(skb)) {
-               if (tailen <= skb_availroom(skb)) {
+               if (tailen <= skb_tailroom(skb)) {
                        nfrags = 1;
                        trailer = skb;
                        tail = skb_tail_pointer(trailer);
-- 
2.7.4