[patch 50/51] ehea: fix invalid pointer access

[Greg KH]

2.6.29-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Hannes Hering <hering2@xxxxxxxxxx>

commit 0b2febf38a33d7c40fb7bb4a58c113a1fa33c412 upstream.

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@xxxxxxxxxx>
Signed-off-by: Jan-Bernd Themann <themann@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/net/ehea/ehea_main.c |   31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

--- a/drivers/net/ehea/ehea_main.c
+++ b/drivers/net/ehea/ehea_main.c
@@ -529,14 +529,17 @@ static inline struct sk_buff *get_skb_by
 	x &= (arr_len - 1);
 
 	pref = skb_array[x];
-	prefetchw(pref);
-	prefetchw(pref + EHEA_CACHE_LINE);
+	if (pref) {
+		prefetchw(pref);
+		prefetchw(pref + EHEA_CACHE_LINE);
+
+		pref = (skb_array[x]->data);
+		prefetch(pref);
+		prefetch(pref + EHEA_CACHE_LINE);
+		prefetch(pref + EHEA_CACHE_LINE * 2);
+		prefetch(pref + EHEA_CACHE_LINE * 3);
+	}
 
-	pref = (skb_array[x]->data);
-	prefetch(pref);
-	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;
@@ -553,12 +556,14 @@ static inline struct sk_buff *get_skb_by
 	x &= (arr_len - 1);
 
 	pref = skb_array[x];
-	prefetchw(pref);
-	prefetchw(pref + EHEA_CACHE_LINE);
-
-	pref = (skb_array[x]->data);
-	prefetchw(pref);
-	prefetchw(pref + EHEA_CACHE_LINE);
+	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;


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