Commit 76fecd82 authored by Eric W. Biederman's avatar Eric W. Biederman Committed by David S. Miller

mpls: In mpls_egress verify the packet length.

Reobert Shearman noticed that mpls_egress is failing to verify that
the bytes to be examined are in fact present in the packet before
mpls_egress reads those bytes.

As suggested by David Miller reduce this to a single pskb_may_pull
call so that we don't do unnecessary work in the fast path.
Reported-by: default avatarRobert Shearman <rshearma@brocade.com>
Signed-off-by: default avatar"Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 2c29b235
...@@ -92,9 +92,24 @@ static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb, ...@@ -92,9 +92,24 @@ static bool mpls_egress(struct mpls_route *rt, struct sk_buff *skb,
* The strange cases if we choose to support them will require * The strange cases if we choose to support them will require
* manual configuration. * manual configuration.
*/ */
struct iphdr *hdr4 = ip_hdr(skb); struct iphdr *hdr4;
bool success = true; bool success = true;
/* The IPv4 code below accesses through the IPv4 header
* checksum, which is 12 bytes into the packet.
* The IPv6 code below accesses through the IPv6 hop limit
* which is 8 bytes into the packet.
*
* For all supported cases there should always be at least 12
* bytes of packet data present. The IPv4 header is 20 bytes
* without options and the IPv6 header is always 40 bytes
* long.
*/
if (!pskb_may_pull(skb, 12))
return false;
/* Use ip_hdr to find the ip protocol version */
hdr4 = ip_hdr(skb);
if (hdr4->version == 4) { if (hdr4->version == 4) {
skb->protocol = htons(ETH_P_IP); skb->protocol = htons(ETH_P_IP);
csum_replace2(&hdr4->check, csum_replace2(&hdr4->check,
......
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