trace-graph: Fix saved pointer corruption in update_last_record()

The saved pointer was created with tracecmd_peek_data() and then set_cpu_to_time()
was called freeing the saved pointer. We could simply reference the pointer if
need be, but using tracecmd_read_data() is a better solution.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/trace-plot-task.c b/trace-plot-task.c
index 552f274..9ca97a3 100644
--- a/trace-plot-task.c
+++ b/trace-plot-task.c
@@ -376,20 +376,23 @@ static void update_last_record(struct graph_info *ginfo,
                 } else {
                         static int once;
 
-                        saved = tracecmd_peek_data(handle, cpu);
+                        saved = tracecmd_read_data(handle, cpu);
                         set_cpu_to_time(cpu, ginfo, ts);
                         t2record = tracecmd_read_data(handle, cpu);
                         trecord = tracecmd_read_prev(handle, t2record);
                         free_record(t2record);
                         /* reset cursor back to what it was */
-                        if (saved)
+                        if (saved) {
                                 tracecmd_set_cursor(handle, cpu, saved->offset);
-                        else {
+                                free_record(saved);
+                        } else {
                                 saved = tracecmd_read_data(handle, cpu);
                                 if (!once && saved) {
                                         once++;
                                         warning("failed to reset cursor to end!");
                                 }
+                                /* saved should always be NULL */
+                                free_record(saved);
                         }
                 }
                 if (!trecord)