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

[Leo Yan]

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....@linaro.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