perf hists browser: Fix potential NULL pointer dereference found by the smatch tool

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@linaro.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/20190708143937.7722-2-leo.yan@linaro.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 11 insertions, 4 deletions

diff --git a/tools/perf/ui/browsers/hists.c b/tools/perf/ui/browsers/hists.c
index 85581cfb9112..a94eb0755e8b 100644
--- a/tools/perf/ui/browsers/hists.c
+++ b/tools/perf/ui/browsers/hists.c
@@ -639,7 +639,11 @@ 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)
@@ -2821,7 +2825,7 @@ 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];
@@ -3087,7 +3091,9 @@ 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;
@@ -3271,7 +3277,8 @@ 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 &&