[tip:perf/core] perf evlist: Fix alloc_mmap() failure path

[tip-bot for Wang Nan]

Commit-ID:  946ae1d41d4b0c77b9f63b4a0393d8a1283a7f9d
Gitweb:     http://git.kernel.org/tip/946ae1d41d4b0c77b9f63b4a0393d8a1283a7f9d
Author:     Wang Nan <wangnan0@xxxxxxxxxx>
AuthorDate: Tue, 31 May 2016 13:06:15 +0000
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Fri, 3 Jun 2016 14:53:46 -0300

perf evlist: Fix alloc_mmap() failure path

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

Signed-off-by: Wang Nan <wangnan0@xxxxxxxxxx>
Acked-by: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
Cc: He Kuang <hekuang@xxxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Zefan Li <lizefan@xxxxxxxxxx>
Cc: pi3orama@xxxxxxx
Fixes: d4c6fb36ac2c ("perf evsel: Record fd into perf_mmap")
Link: http://lkml.kernel.org/r/1464699975-230440-1-git-send-email-wangnan0@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 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 {