[PATCH] perf synthetic events: Avoid write of uninitialized memory.

[Ian Rogers]

Account for alignment bytes in the zero-ing memset.

Signed-off-by: Ian Rogers <irog...@google.com>
---
 tools/perf/util/synthetic-events.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/synthetic-events.c 
b/tools/perf/util/synthetic-events.c
index b698046ec2db..31bf3dd6a1e0 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -424,7 +424,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool 
*tool,
 
        while (!io.eof) {
                static const char anonstr[] = "//anon";
-               size_t size;
+               size_t size, aligned_size;
 
                /* ensure null termination since stack will be reused. */
                event->mmap2.filename[0] = '\0';
@@ -484,11 +484,12 @@ int perf_event__synthesize_mmap_events(struct perf_tool 
*tool,
                }
 
                size = strlen(event->mmap2.filename) + 1;
-               size = PERF_ALIGN(size, sizeof(u64));
+               aligned_size = PERF_ALIGN(size, sizeof(u64));
                event->mmap2.len -= event->mmap.start;
                event->mmap2.header.size = (sizeof(event->mmap2) -
-                                       (sizeof(event->mmap2.filename) - size));
-               memset(event->mmap2.filename + size, 0, machine->id_hdr_size);
+                                       (sizeof(event->mmap2.filename) - 
aligned_size));
+               memset(event->mmap2.filename + size, 0, machine->id_hdr_size +
+                       (aligned_size - size));
                event->mmap2.header.size += machine->id_hdr_size;
                event->mmap2.pid = tgid;
                event->mmap2.tid = pid;
-- 
2.30.1.766.gb4fecdf3b7-goog