[UDP]: Fix length check.

Rémi Denis-Courmont wrote:
> Right. By the way, shouldn't "len" rather be signed in there?
> 
> 		unsigned int len;
> 
> 		/* if we're overly short, let UDP handle it */
> 		len = skb->len - sizeof(struct udphdr);
> 		if (len <= 0)
> 			goto udp;

It should, but the < 0 case can't happen since __udp4_lib_rcv
already makes sure that we have at least a complete UDP header.

Anyways, this patch fixes it.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 7 deletions

diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 4ec4a25a8d0c..28355350fb62 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -951,14 +951,10 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
                  * >0 if skb should be passed on to UDP.
                  * <0 if skb should be resubmitted as proto -N
                  */
-                unsigned int len;
 
                 /* if we're overly short, let UDP handle it */
-                len = skb->len - sizeof(struct udphdr);
-                if (len <= 0)
-                        goto udp;
-
-                if (up->encap_rcv != NULL) {
+                if (skb->len > sizeof(struct udphdr) &&
+                    up->encap_rcv != NULL) {
                         int ret;
 
                         ret = (*up->encap_rcv)(sk, skb);
@@ -971,7 +967,6 @@ int udp_queue_rcv_skb(struct sock * sk, struct sk_buff *skb)
                 /* FALLTHROUGH -- it's a UDP Packet */
         }
 
-udp:
         /*
          *      UDP-Lite specific tests, ignored on UDP sockets
          */