[PATCH] perf tools: Fix perf_evlist__alloc_mmap() failure path

[Wang Nan]

If zalloc fail, setting evlist->mmap[i].fd is unsafe.
perf_evlist__alloc_mmap() should fail right after zalloc() fail.

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
---
 tools/perf/util/evlist.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index e0f3094..1b918aa 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -946,9 +946,12 @@ static int perf_evlist__alloc_mmap(struct perf_evlist *evlist)
 	if (cpu_map__empty(evlist->cpus))
 		evlist->nr_mmaps = thread_map__nr(evlist->threads);
 	evlist->mmap = zalloc(evlist->nr_mmaps * sizeof(struct perf_mmap));
+	if (!evlist->mmap)
+		return -ENOMEM;
+
 	for (i = 0; i < evlist->nr_mmaps; i++)
 		evlist->mmap[i].fd = -1;
-	return evlist->mmap != NULL ? 0 : -ENOMEM;
+	return 0;
 }
 
 struct mmap_params {
-- 
1.8.3.4