linux-kernel - [PATCH 5.11 233/254] perf synthetic events: Avoid write of uninitialized memory when generating PERF_RECORD

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Date:   Mon, 29 Mar 2021 09:59:09 +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, Ian Rogers <irogers@...gle.com>,
        Jiri Olsa <jolsa@...hat.com>, Ingo Molnar <mingo@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Mark Rutland <mark.rutland@....com>,
        Namhyung Kim <namhyung@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Stephane Eranian <eranian@...gle.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.11 233/254] perf synthetic events: Avoid write of uninitialized memory when generating PERF_RECORD_MMAP* records

From: Ian Rogers <irogers@...gle.com>

[ 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@...gle.com>
Acked-by: Jiri Olsa <jolsa@...hat.com>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
Cc: Mark Rutland <mark.rutland@....com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Stephane Eranian <eranian@...gle.com>
Link: http://lore.kernel.org/lkml/20210309234945.419254-1-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 2947e3f3c6d9..dda0a6a3173d 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