perf tools: Validate perf event header size

The 'size' variable includes the header so must be at least
'sizeof(struct perf_event_header)'.  Error out immediately if that is
not the case.  Also don't byte-swap the header until it is actually
"fetched" from the mmap region.

Signed-off-by: Adrian Hunter <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jiri Olsa <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>

diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index 6b71b88f95fa6f0ea1aae44fb9c1b5db90117822..951a1cfb317c99c0a11739235c145c97b55ea92c 100644 (file)
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1094,8 +1094,10 @@ more:
                perf_event_header__bswap(&event->header);
 
        size = event->header.size;
-       if (size == 0)
-               size = 8;
+       if (size < sizeof(struct perf_event_header)) {
+               pr_err("bad event header size\n");
+               goto out_err;
+       }
 
        if (size > cur_size) {
                void *new = realloc(buf, size);
@@ -1164,8 +1166,12 @@ fetch_mmaped_event(struct perf_session *session,
        if (session->header.needs_swap)
                perf_event_header__bswap(&event->header);
 
-       if (head + event->header.size > mmap_size)
+       if (head + event->header.size > mmap_size) {
+               /* We're not fetching the event so swap back again */
+               if (session->header.needs_swap)
+                       perf_event_header__bswap(&event->header);
                return NULL;
+       }
 
        return event;
 }
@@ -1245,7 +1251,7 @@ more:
 
        size = event->header.size;
 
-       if (size == 0 ||
+       if (size < sizeof(struct perf_event_header) ||
            perf_session__process_event(session, event, tool, file_pos) < 0) {
                pr_err("%#" PRIx64 " [%#x]: failed to process type: %d\n",
                       file_offset + head, event->header.size,