[PATCH] perf: Add NULL pointer check for cpu_map iteration and NULL assignment for all_cpus.

[zhe.he]

From: He Zhe <zhe.he@xxxxxxxxxxxxx>

NULL pointer may be passed to perf_cpu_map__cpu and then cause crash,
such as the one commit cb71f7d43ece ("libperf: Setup initial evlist::all_cpus value")
fix.

Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
---
 tools/perf/lib/cpumap.c | 2 +-
 tools/perf/lib/evlist.c | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/perf/lib/cpumap.c b/tools/perf/lib/cpumap.c
index f93f4e7..ca02150 100644
--- a/tools/perf/lib/cpumap.c
+++ b/tools/perf/lib/cpumap.c
@@ -247,7 +247,7 @@ struct perf_cpu_map *perf_cpu_map__new(const char *cpu_list)
 
 int perf_cpu_map__cpu(const struct perf_cpu_map *cpus, int idx)
 {
-	if (idx < cpus->nr)
+	if (cpus && idx < cpus->nr)
 		return cpus->map[idx];
 
 	return -1;
diff --git a/tools/perf/lib/evlist.c b/tools/perf/lib/evlist.c
index 5b9f2ca..f87a239 100644
--- a/tools/perf/lib/evlist.c
+++ b/tools/perf/lib/evlist.c
@@ -127,6 +127,7 @@ void perf_evlist__exit(struct perf_evlist *evlist)
 	perf_cpu_map__put(evlist->cpus);
 	perf_thread_map__put(evlist->threads);
 	evlist->cpus = NULL;
+	evlist->all_cpus = NULL;
 	evlist->threads = NULL;
 	fdarray__exit(&evlist->pollfd);
 }
-- 
2.7.4