[PATCH 4.9 12/25] perf header: Fix handling of PERF_EVENT_UPDATE__SCALE

From: Greg Kroah-Hartman
Date: Thu Jul 13 2017 - 11:41:28 EST

4.9-stable review patch. If anyone has any objections, please let me know.


From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

commit 8434a2ec13d5c8cb25716950bfbf7c9d7b64628a upstream.

In commit daeecbc0c431 ("perf tools: Add event_update event scale type"), the
handling of PERF_EVENT_UPDATE__SCALE cast struct event_update_event->data to a
pointer to event_update_event_scale, uses some field from this casted struct
and then ends up falling through to the handling of another event type,
PERF_EVENT_UPDATE__CPUS were it casts that ev->data to yet another type, oops,
fix it by inserting the missing break.

Noticed when building perf using gcc 7 on Fedora Rawhide:

util/header.c: In function 'perf_event__process_event_update':
util/header.c:3207:16: error: this statement may fall through [-Werror=implicit-fallthrough=]
evsel->scale = ev_scale->scale;
util/header.c:3208:2: note: here

This wasn't noticed because probably PERF_EVENT_UPDATE__CPUS comes after
PERF_EVENT_UPDATE__SCALE, so we would just create a bogus evsel->own_cpus when
processing a PERF_EVENT_UPDATE__SCALE to then leak it and create a new cpu map
with the correct data.

Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Fixes: daeecbc0c431 ("perf tools: Add event_update event scale type")
Link: http://lkml.kernel.org/n/tip-lukcf9hdj092ax2914ss95at@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

tools/perf/util/header.c | 1 +
1 file changed, 1 insertion(+)

--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3184,6 +3184,7 @@ int perf_event__process_event_update(str
ev_scale = (struct event_update_event_scale *) ev->data;
evsel->scale = ev_scale->scale;
+ break;
ev_cpus = (struct event_update_event_cpus *) ev->data;