linux-kernel - [PATCH v1 06/11] perf hists: Smatch: Fix potential NULL pointer dereference

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Date:   Tue,  2 Jul 2019 18:34:15 +0800
From:   Leo Yan <leo.yan@...aro.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Mathieu Poirier <mathieu.poirier@...aro.org>,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Andi Kleen <ak@...ux.intel.com>,
        "David S. Miller" <davem@...emloft.net>,
        Davidlohr Bueso <dave@...olabs.net>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Jin Yao <yao.jin@...ux.intel.com>,
        Song Liu <songliubraving@...com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexios Zavras <alexios.zavras@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Changbin Du <changbin.du@...el.com>,
        Eric Saint-Etienne <eric.saint.etienne@...cle.com>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Thomas Richter <tmricht@...ux.ibm.com>,
        Alexey Budankov <alexey.budankov@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     Leo Yan <leo.yan@...aro.org>
Subject: [PATCH v1 06/11] perf hists: Smatch: Fix potential NULL pointer dereference

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 <leo.yan@...aro.org>
---
 tools/perf/ui/browsers/hists.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 3421ecbdd3f0..2ba33040ddd8 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -638,7 +638,9 @@ int hist_browser__run(struct hist_browser *browser, const char *help,
 		switch (key) {
 		case K_TIMER: {
 			u64 nr_entries;
-			hbt->timer(hbt->arg);
+
+			if (hbt)
+				hbt->timer(hbt->arg);
 
 			if (hist_browser__has_filter(browser) ||
 			    symbol_conf.report_hierarchy)
@@ -2819,7 +2821,7 @@ 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 +3087,9 @@ 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 +3273,8 @@ 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 &&
-- 
2.17.1