diff mbox

[3.8,52/81] ipv6: gre: correct calculation of max_headroom

Message ID 1383069882-11437-53-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa Oct. 29, 2013, 6:04 p.m. UTC 
3.8.13.12 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Hannes Frederic Sowa <hannes@stressinduktion.org>

[ Upstream commit 3da812d860755925da890e8c713f2d2e2d7b1bae ]

gre_hlen already accounts for sizeof(struct ipv6_hdr) + gre header,
so initialize max_headroom to zero. Otherwise the

	if (encap_limit >= 0) {
		max_headroom += 8;
		mtu -= 8;
	}

increments an uninitialized variable before max_headroom was reset.

Found with coverity: 728539

Cc: Dmitry Kozlov <xeb@mail.ru>
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
 net/ipv6/ip6_gre.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
diff mbox

Patch

diff --git a/net/ipv6/ip6_gre.c b/net/ipv6/ip6_gre.c
index a4c5ae7..be42860 100644
--- a/net/ipv6/ip6_gre.c
+++ b/net/ipv6/ip6_gre.c
@@ -659,7 +659,7 @@  static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 	struct ip6_tnl *tunnel = netdev_priv(dev);
 	struct net_device *tdev;    /* Device to other host */
 	struct ipv6hdr  *ipv6h;     /* Our new IP header */
-	unsigned int max_headroom;  /* The extra header space needed */
+	unsigned int max_headroom = 0; /* The extra header space needed */
 	int    gre_hlen;
 	struct ipv6_tel_txoption opt;
 	int    mtu;
@@ -733,7 +733,7 @@  static netdev_tx_t ip6gre_xmit2(struct sk_buff *skb,
 			tunnel->err_count = 0;
 	}
 
-	max_headroom = LL_RESERVED_SPACE(tdev) + gre_hlen + dst->header_len;
+	max_headroom += LL_RESERVED_SPACE(tdev) + gre_hlen + dst->header_len;
 
 	if (skb_headroom(skb) < max_headroom || skb_shared(skb) ||
 	    (skb_cloned(skb) && !skb_clone_writable(skb, 0))) {