[PATCH 2.6.30-rc5] ehea: fix invalid pointer access

[Hannes Hering]

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 <heri...@de.ibm.com>
Signed-off-by: Jan-Bernd Themann <them...@de.ibm.com>
---

diff -Nurp -X dontdiff linux-2.6.30-rc4/drivers/net/ehea/ehea.h 
patched_kernel/drivers/net/ehea/ehea.h
--- linux-2.6.30-rc4/drivers/net/ehea/ehea.h    2009-05-04 09:54:42.000000000 
+0200
+++ patched_kernel/drivers/net/ehea/ehea.h      2009-05-04 10:40:11.000000000 
+0200
@@ -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
diff -Nurp -X dontdiff linux-2.6.30-rc4/drivers/net/ehea/ehea_main.c 
patched_kernel/drivers/net/ehea/ehea_main.c
--- linux-2.6.30-rc4/drivers/net/ehea/ehea_main.c       2009-05-04 
09:54:42.000000000 +0200
+++ patched_kernel/drivers/net/ehea/ehea_main.c 2009-05-04 10:40:11.000000000 
+0200
@@ -545,14 +545,17 @@ 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;
@@ -569,12 +572,14 @@ 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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