[tip:perf/core] perf header: Fix unchecked usage of strncpy() - tip-bot for Arnaldo Carvalho de Melo

From: tip-bot for Arnaldo Carvalho de Melo <tipbot@zytor.com>
To: linux-tip-commits@vger.kernel.org
Cc: mingo@kernel.org, acme@redhat.com, linux-kernel@vger.kernel.org,
	tglx@linutronix.de, jolsa@kernel.org, namhyung@kernel.org,
	adrian.hunter@intel.com, hpa@zytor.com
Subject: [tip:perf/core] perf header: Fix unchecked usage of strncpy()
Date: Fri, 14 Dec 2018 12:54:47 -0800	[thread overview]
Message-ID: <tip-wycz66iy8dl2z3yifgqf894p@git.kernel.org> (raw)

Commit-ID:  8b3ff080ebb16abcb4766e916dc020add0f4df39
Gitweb:     https://git.kernel.org/tip/8b3ff080ebb16abcb4766e916dc020add0f4df39
Author:     Arnaldo Carvalho de Melo <acme@redhat.com>
AuthorDate: Thu, 6 Dec 2018 11:09:46 -0300
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 6 Dec 2018 16:41:06 -0300

perf header: Fix unchecked usage of strncpy()

The strncpy() function may leave the destination string buffer
unterminated, better use strlcpy() that we have a __weak fallback
implementation for systems without it.

This fixes this warning on an Alpine Linux Edge system with gcc 8.2:

  util/header.c: In function 'perf_event__synthesize_event_update_name':
  util/header.c:3625:2: error: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
    strncpy(ev->data, evsel->name, len);
    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  util/header.c:3618:15: note: length computed here
    size_t len = strlen(evsel->name);
                 ^~~~~~~~~~~~~~~~~~~

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Fixes: a6e5281780d1 ("perf tools: Add event_update event unit type")
Link: https://lkml.kernel.org/n/tip-wycz66iy8dl2z3yifgqf894p@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/util/header.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index c87cfe6b7c96..1171d8400bf4 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3622,7 +3622,7 @@ perf_event__synthesize_event_update_name(struct perf_tool *tool,
 	if (ev == NULL)
 		return -ENOMEM;
 
-	strncpy(ev->data, evsel->name, len);
+	strlcpy(ev->data, evsel->name, len + 1);
 	err = process(tool, (union perf_event*) ev, NULL, NULL);
 	free(ev);
 	return err;
