ehea: fix invalid pointer access

This patch fixes an invalid pointer access in case the receive queue
holds no pointer to the next skb when the queue is empty.
Signed-off-by: Hannes Hering <hering2@de.ibm.com>
Signed-off-by: Jan-Bernd Themann <themann@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ehea/ehea.h

@@ -40,7 +40,7 @@
 #include <asm/io.h>
 
 #define DRV_NAME	"ehea"
-#define DRV_VERSION	"EHEA_0100"
+#define DRV_VERSION	"EHEA_0101"
 
 /* eHEA capability flags */
 #define DLPAR_PORT_ADD_REM 1

drivers/net/ehea/ehea_main.c

@@ -545,6 +545,7 @@ static inline struct sk_buff *get_skb_by_index(struct sk_buff **skb_array,
 	x &= (arr_len - 1);
 
 	pref = skb_array[x];
+	if (pref) {
 		prefetchw(pref);
 		prefetchw(pref + EHEA_CACHE_LINE);
 
@@ -553,6 +554,8 @@ static inline struct sk_buff *get_skb_by_index(struct sk_buff **skb_array,
 		prefetch(pref + EHEA_CACHE_LINE);
 		prefetch(pref + EHEA_CACHE_LINE * 2);
 		prefetch(pref + EHEA_CACHE_LINE * 3);
+	}
+
 	skb = skb_array[skb_index];
 	skb_array[skb_index] = NULL;
 	return skb;
@@ -569,12 +572,14 @@ static inline struct sk_buff *get_skb_by_index_ll(struct sk_buff **skb_array,
 	x &= (arr_len - 1);
 
 	pref = skb_array[x];
+	if (pref) {
 		prefetchw(pref);
 		prefetchw(pref + EHEA_CACHE_LINE);
 
 		pref = (skb_array[x]->data);
 		prefetchw(pref);
 		prefetchw(pref + EHEA_CACHE_LINE);
+	}
 
 	skb = skb_array[wqe_index];
 	skb_array[wqe_index] = NULL;