perf ordered_events: Fix crash in ordered_events__free

Song Liu reported crash in 'perf record':

  > #0  0x0000000000500055 in ordered_events(float, long double,...)(...) ()
  > #1  0x0000000000500196 in ordered_events.reinit ()
  > #2  0x00000000004fe413 in perf_session.process_events ()
  > #3  0x0000000000440431 in cmd_record ()
  > #4  0x00000000004a439f in run_builtin ()
  > #5  0x000000000042b3e5 in main ()"

This can happen when we get out of buffers during event processing.

The subsequent ordered_events__free() call assumes oe->buffer != NULL
and crashes. Add a check to prevent that.

Reported-by: Song Liu <liu.song.a23@gmail.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Reviewed-by: Song Liu <liu.song.a23@gmail.com>
Tested-by: Song Liu <liu.song.a23@gmail.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20190117113017.12977-1-jolsa@kernel.org
Fixes: d5ceb62b3654 ("perf ordered_events: Add 'struct ordered_events_buffer' layer")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c
index 8975895..ea523d3 100644 (file)
--- a/tools/perf/util/ordered-events.c
+++ b/tools/perf/util/ordered-events.c
@@ -391,8 +391,10 @@ void ordered_events__free(struct ordered_events *oe)
         * Current buffer might not have all the events allocated
         * yet, we need to free only allocated ones ...
         */
-       list_del(&oe->buffer->list);
-       ordered_events_buffer__free(oe->buffer, oe->buffer_idx, oe);
+       if (oe->buffer) {
+               list_del(&oe->buffer->list);
+               ordered_events_buffer__free(oe->buffer, oe->buffer_idx, oe);
+       }
 
        /* ... and continue with the rest */
        list_for_each_entry_safe(buffer, tmp, &oe->to_free, list) {