Subject: [PATCH AUTOSEL 5.2 130/171] perf hists browser: Fix potential NULL pointer dereference found by the smatch tool

From: Sasha Levin <[email-masked]>
Date: Thu, 18 Jul 2019 23:56:01 -0400

From: Leo Yan <[email-masked]>

[ Upstream commit ceb75476db1617a88cc29b09839acacb69aa076e ]

Based on the following report from Smatch, fix the potential
NULL pointer dereference check.

  tools/perf/ui/browsers/hists.c:641
  hist_browser__run() error: we previously assumed 'hbt' could be
  null (see line 625)

  tools/perf/ui/browsers/hists.c:3088
  perf_evsel__hists_browse() error: we previously assumed
  'browser->he_selection' could be null (see line 2902)

  tools/perf/ui/browsers/hists.c:3272
  perf_evsel_menu__run() error: we previously assumed 'hbt' could be
  null (see line 3260)

This patch firstly validating the pointers before access them, so can
fix potential NULL pointer dereference.

Signed-off-by: Leo Yan <[email-masked]>
Acked-by: Jiri Olsa <[email-masked]>
Cc: Adrian Hunter <[email-masked]>
Cc: Alexander Shishkin <[email-masked]>
Cc: Andi Kleen <[email-masked]>
Cc: Mathieu Poirier <[email-masked]>
Cc: Namhyung Kim <[email-masked]>
Cc: Suzuki Poulouse <[email-masked]>
Cc: [email-masked]
Link: http://lkml.kernel.org/r/[email-masked]
Signed-off-by: Arnaldo Carvalho de Melo <[email-masked]>
Signed-off-by: Sasha Levin <[email-masked]>
---
 tools/perf/ui/browsers/hists.c | 15 +++++++++++----
 1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 3421ecbdd3f0..c1dd9b54dc6e 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -638,7 +638,11 @@ int hist_browser__run(struct hist_browser *browser, const char *help,
 		switch (key) {
 		case K_TIMER: {
 			u64 nr_entries;
-			hbt->timer(hbt->arg);
+
+			WARN_ON_ONCE(!hbt);
+
+			if (hbt)
+				hbt->timer(hbt->arg);
 
 			if (hist_browser__has_filter(browser) ||
 			    symbol_conf.report_hierarchy)
@@ -2819,7 +2823,7 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
 {
 	struct hists *hists = evsel__hists(evsel);
 	struct hist_browser *browser = perf_evsel_browser__new(evsel, hbt, env, annotation_opts);
-	struct branch_info *bi;
+	struct branch_info *bi = NULL;
 #define MAX_OPTIONS  16
 	char *options[MAX_OPTIONS];
 	struct popup_action actions[MAX_OPTIONS];
@@ -3085,7 +3089,9 @@ static int perf_evsel__hists_browse(struct perf_evsel *evsel, int nr_events,
 			goto skip_annotation;
 
 		if (sort__mode == SORT_MODE__BRANCH) {
-			bi = browser->he_selection->branch_info;
+
+			if (browser->he_selection)
+				bi = browser->he_selection->branch_info;
 
 			if (bi == NULL)
 				goto skip_annotation;
@@ -3269,7 +3275,8 @@ static int perf_evsel_menu__run(struct perf_evsel_menu *menu,
 
 		switch (key) {
 		case K_TIMER:
-			hbt->timer(hbt->arg);
+			if (hbt)
+				hbt->timer(hbt->arg);
 
 			if (!menu->lost_events_warned &&
 			    menu->lost_events &&
-- 
2.20.1

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