perf record: Zero out mmap_array to fix segfault

Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Tested-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Zhang Yanmin <yanmin_zhang@linux.intel.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <1269557941-15617-6-git-send-email-acme@infradead.org>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 5f3ac9f..4abdd9b 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -1371,7 +1371,7 @@
 	for (i = 0; i < MAX_NR_CPUS; i++) {
 		for (j = 0; j < MAX_COUNTERS; j++) {
 			fd[i][j] = malloc(sizeof(int)*thread_num);
-			mmap_array[i][j] = malloc(
+			mmap_array[i][j] = zalloc(
 				sizeof(struct mmap_data)*thread_num);
 			if (!fd[i][j] || !mmap_array[i][j])
 				return -ENOMEM;