[PATCH 1/6] perf tools: Check we are able to read the event size on mmap

[Frederic Weisbecker <fweisbec@gmail.com>]

Check we have enough mmaped space to read the current event
size from its headers, otherwise we may dereference some
hell there.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
---
 tools/perf/util/session.c |    7 +++++++
 1 files changed, 7 insertions(+), 0 deletions(-)

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index fff6674..61746b5 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1007,6 +1007,13 @@ remap:
 	file_pos = file_offset + head;
 
 more:
+	/*
+	 * Ensure we have enough space remaining to read
+	 * the size of the event in the headers.
+	 */
+	if (head + sizeof(event->header) > mmap_size)
+		goto remap;
+
 	event = (union perf_event *)(buf + head);
 
 	if (session->header.needs_swap)
-- 
1.7.3.2