--- 7fa9c7ad3d3b5b7efbe4c612511425628900a138
+++ d00681646d1de54b31101ae8bbab2a0a209cc4fa
@@ -81,6 +81,41 @@ struct compat_x25_subscrip_struct {
 };
 #endif
 
+
+int x25_parse_address_block(struct sk_buff *skb,
+		struct x25_address *called_addr,
+		struct x25_address *calling_addr)
+{
+	unsigned char len;
+	int needed;
+	int rc;
+
+	if (skb->len < 1) {
+		/* packet has no address block */
+		rc = 0;
+		goto empty;
+	}
+
+	len = *skb->data;
+	needed = 1 + (len >> 4) + (len & 0x0f);
+
+	if (skb->len < needed) {
+		/* packet is too short to hold the addresses it claims
+		   to hold */
+		rc = -1;
+		goto empty;
+	}
+
+	return x25_addr_ntoa(skb->data, called_addr, calling_addr);
+
+empty:
+	*called_addr->x25_addr = 0;
+	*calling_addr->x25_addr = 0;
+
+	return rc;
+}
+
+
 int x25_addr_ntoa(unsigned char *p, struct x25_address *called_addr,
 		  struct x25_address *calling_addr)
 {
@@ -871,16 +906,26 @@ int x25_rx_call_request(struct sk_buff *
 	/*
 	 *	Extract the X.25 addresses and convert them to ASCII strings,
 	 *	and remove them.
+	 *
+	 *	Address block is mandatory in call request packets
 	 */
-	addr_len = x25_addr_ntoa(skb->data, &source_addr, &dest_addr);
+	addr_len = x25_parse_address_block(skb, &source_addr, &dest_addr);
+	if (addr_len <= 0)
+		goto out_clear_request;
 	skb_pull(skb, addr_len);
 
 	/*
 	 *	Get the length of the facilities, skip past them for the moment
 	 *	get the call user data because this is needed to determine
 	 *	the correct listener
+	 *
+	 *	Facilities length is mandatory in call request packets
 	 */
+	if (skb->len < 1)
+		goto out_clear_request;
 	len = skb->data[0] + 1;
+	if (skb->len < len)
+		goto out_clear_request;
 	skb_pull(skb,len);
 
 	/*