Fix malloc buffer overrun for unordered CPUs in sysfs

For some ordering of CPUs in sysfs the cache read code could overrun
its internal CPU array. Make sure the array is always correctly sized.

Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/cache.c b/cache.c
index 4a1374f..d038751 100644
--- a/cache.c
+++ b/cache.c
@@ -54,7 +54,9 @@ static void more_cpus(int cpu)
 	int old = cachelen;
 	if (!cachelen)
 		cachelen = MIN_CPUS/2;	
-	cachelen *= 2;
+	if (cachelen < cpu)
+		cachelen = cpu + 1;
+	cachelen = cachelen * 2;
 	caches = xrealloc(caches, cachelen * sizeof(struct cache *));
 	memset(caches + old, 0, (cachelen - old) * sizeof(struct cache *));
 }
@@ -129,8 +131,9 @@ static int read_caches(void)
 				numindex = st.st_nlink - 2;
 				if (numindex < 0)
 					numindex = MIN_INDEX;
-				if (cachelen <= cpu)
+				if (cpu >= cachelen)
 					more_cpus(cpu);
+				assert(cpu < cachelen);
 				caches[cpu] = xalloc(sizeof(struct cache) * 
 						     (numindex+1));
 				for (i = 0; i < numindex; i++) {