linux-kernel - [PATCH 4.9 12/25] perf header: Fix handling of PERF_EVENT_UPDATE_

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Message-Id: <20170713154002.354512800@linuxfoundation.org>
Date:   Thu, 13 Jul 2017 17:40:26 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, David Ahern <dsahern@...il.com>,
        Jiri Olsa <jolsa@...nel.org>, Kan Liang <kan.liang@...el.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 4.9 12/25] perf header: Fix handling of PERF_EVENT_UPDATE__SCALE

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

------------------

From: Arnaldo Carvalho de Melo <acme@...hat.com>

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
    case PERF_EVENT_UPDATE__CPUS:
    ^~~~

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@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Kan Liang <kan.liang@...el.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Fixes: daeecbc0c431 ("perf tools: Add event_update event scale type")
Link: http://lkml.kernel.org/n/tip-lukcf9hdj092ax2914ss95at@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 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
 	case PERF_EVENT_UPDATE__SCALE:
 		ev_scale = (struct event_update_event_scale *) ev->data;
 		evsel->scale = ev_scale->scale;
+		break;
 	case PERF_EVENT_UPDATE__CPUS:
 		ev_cpus = (struct event_update_event_cpus *) ev->data;