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

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

net/mpls/af_mpls.c

+16 −1
Original line number Diff line number Diff line
@@ -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

	 * manual configuration.

	 */

	struct iphdr *hdr4 = ip_hdr(skb);

	struct iphdr *hdr4;

	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) {

		skb->protocol = htons(ETH_P_IP);

		csum_replace2(&hdr4->check,