[PATCH 5.10 199/221] perf synthetic events: Avoid write of uninitialized memory when generating PERF_RECORD_MMAP* records

From: Greg Kroah-Hartman
Date: Mon Mar 29 2021 - 04:44:19 EST


From: Ian Rogers <irogers@xxxxxxxxxx>

[ Upstream commit 2a76f6de07906f0bb5f2a13fb02845db1695cc29 ]

Account for alignment bytes in the zero-ing memset.

Fixes: 1a853e36871b533c ("perf record: Allow specifying a pid to record")
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
Cc: Mark Rutland <mark.rutland@xxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Link: http://lore.kernel.org/lkml/20210309234945.419254-1-irogers@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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 d9c624377da7..b4cf6dd57dd6 100644
--- a/tools/perf/util/synthetic-events.c
+++ b/tools/perf/util/synthetic-events.c
@@ -384,7 +384,7 @@ 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';
@@ -444,11 +444,12 @@ 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