linux-kernel - [tip:perf/core] perf dso: Fix unchecked usage of strncpy()

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Date:   Tue, 18 Dec 2018 06:20:32 -0800
From:   tip-bot for Arnaldo Carvalho de Melo <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     acme@...hat.com, tglx@...utronix.de, hpa@...or.com,
        linux-kernel@...r.kernel.org, jolsa@...nel.org, mingo@...nel.org,
        adrian.hunter@...el.com, namhyung@...nel.org
Subject: [tip:perf/core] perf dso: Fix unchecked usage of strncpy()

Commit-ID:  fca5085c15255bbde203b7322c15f07ebb12f63e
Gitweb:     https://git.kernel.org/tip/fca5085c15255bbde203b7322c15f07ebb12f63e
Author:     Arnaldo Carvalho de Melo <acme@...hat.com>
AuthorDate: Thu, 6 Dec 2018 10:49:46 -0300
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Mon, 17 Dec 2018 14:59:03 -0300

perf dso: 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:

  In function 'decompress_kmodule',
      inlined from 'dso__decompress_kmodule_fd' at util/dso.c:305:9:
  util/dso.c:298:3: error: 'strncpy' destination unchanged after copying no bytes [-Werror=stringop-truncation]
     strncpy(pathname, tmpbuf, len);
     ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    CC       /tmp/build/perf/util/values.o
    CC       /tmp/build/perf/util/debug.o
  cc1: all warnings being treated as errors

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Fixes: c9a8a6131fb6 ("perf tools: Move the temp file processing into decompress_kmodule")
Link: https://lkml.kernel.org/n/tip-tl2hdxj64tt4k8btbi6a0ugw@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/util/dso.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/dso.c b/tools/perf/util/dso.c
index bbed90e5d9bb..cee717a3794f 100644
--- a/tools/perf/util/dso.c
+++ b/tools/perf/util/dso.c
@@ -295,7 +295,7 @@ static int decompress_kmodule(struct dso *dso, const char *name,
 		unlink(tmpbuf);
 
 	if (pathname && (fd >= 0))
-		strncpy(pathname, tmpbuf, len);
+		strlcpy(pathname, tmpbuf, len);
 
 	return fd;
 }