[tip: perf/core] libperf: Add NULL pointer check for cpu_map iteration and NULL assignment for all_cpus.

[tip-bot2 for He Zhe]

The following commit has been merged into the perf/core branch of tip:

Commit-ID:     44d041b7b2c11b6739501fd3763cc6fed62cf0ed
Gitweb:        https://git.kernel.org/tip/44d041b7b2c11b6739501fd3763cc6fed62cf0ed
Author:        He Zhe <zhe.he@xxxxxxxxxxxxx>
AuthorDate:    Sun, 08 Mar 2020 18:59:17 +08:00
Committer:     Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitterDate: Tue, 05 May 2020 16:35:29 -03:00

libperf: Add NULL pointer check for cpu_map iteration and NULL assignment for all_cpus.

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

Signed-off-by: He Zhe <zhe.he@xxxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: Kyle Meyer <meyerk@xxxxxxx>
Link: http://lore.kernel.org/lkml/1583665157-349023-1-git-send-email-zhe.he@xxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/lib/perf/cpumap.c | 2 +-
 tools/lib/perf/evlist.c | 1 +
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/lib/perf/cpumap.c b/tools/lib/perf/cpumap.c
index f93f4e7..ca02150 100644
--- a/tools/lib/perf/cpumap.c
+++ b/tools/lib/perf/cpumap.c
@@ -247,7 +247,7 @@ out:
 
 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/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index def5505..c481b62 100644
--- a/tools/lib/perf/evlist.c
+++ b/tools/lib/perf/evlist.c
@@ -125,6 +125,7 @@ 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);
 }