[PATCH 2/7] perf inject: copy events when reordering events in pipe mode

David Carrillo-Cisneros
2017-04-10T20:16:19Z

__perf_session__process_pipe_events reuses the same memory buffer to
process all events in the pipe.

When reordering is needed (e.g. -b option), events are not immediately
flushed, but kept around until reordering is possible, causing
memory corruption.

The problem is usually observed by a "Unknown sample error" output. It
can easily be reproduced by:

perf record -o - noploop | perf inject -b > output

Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
---
tools/perf/util/ordered-events.c | 3 ++-
tools/perf/util/session.c | 1 +
2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/ordered-events.c b/tools/perf/util/ordered-events.c
index fe84df1875aa..e70e935b1841 100644
--- a/tools/perf/util/ordered-events.c
+++ b/tools/perf/util/ordered-events.c
@@ -79,7 +79,7 @@ static union perf_event *dup_event(struct ordered_events *oe,

static void free_dup_event(struct ordered_events *oe, union perf_event *event)
{
- if (oe->copy_on_queue) {
+ if (event && oe->copy_on_queue) {
oe->cur_alloc_size -= event->header.size;
free(event);
}
@@ -150,6 +150,7 @@ void ordered_events__delete(struct ordered_events *oe, struct ordered_event *eve
list_move(&event->list, &oe->cache);
oe->nr_events--;
free_dup_event(oe, event->event);
+ event->event = NULL;
}

int ordered_events__queue(struct ordered_events *oe, union perf_event *event,
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 24259bc2c598..a25302bc55a8 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1656,6 +1656,7 @@ static int __perf_session__process_pipe_events(struct perf_session *session)
buf = malloc(cur_size);
if (!buf)
return -errno;
+ ordered_events__set_copy_on_queue(oe, true);
more:
event = buf;
err = readn(fd, event, sizeof(struct perf_event_header));
--
2.12.2.715.g7642488e1d-goog