From 54ffd790792898f05e215dce5aa593473e80e92f Mon Sep 17 00:00:00 2001
From: Steffen Klassert <steffen.klassert@secunet.com>
Date: Fri, 25 Aug 2017 07:34:35 +0200
Subject: [PATCH] esp: Fix skb tailroom calculation
Git-commit: 54ffd790792898f05e215dce5aa593473e80e92f
Patch-mainline: v4.13
References: bsc#1051510

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.klassert@secunet.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 net/ipv4/esp4.c |    2 +-
 net/ipv6/esp6.c |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

--- a/net/ipv4/esp4.c
+++ b/net/ipv4/esp4.c
@@ -258,7 +258,7 @@ int esp_output_head(struct xfrm_state *x
 		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);
--- a/net/ipv6/esp6.c
+++ b/net/ipv6/esp6.c
@@ -231,7 +231,7 @@ int esp6_output_head(struct xfrm_state *
 	esph = ip_esp_hdr(skb);
 
 	if (!skb_cloned(skb)) {
-		if (tailen <= skb_availroom(skb)) {
+		if (tailen <= skb_tailroom(skb)) {
 			nfrags = 1;
 			trailer = skb;
 			tail = skb_tail_pointer(trailer);