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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Arnaldo Carvalho de Melo <acme@redhat.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH AUTOSEL 4.19 166/258] perf dso: Fix unchecked usage of strncpy()
Date:   Mon, 28 Jan 2019 10:57:52 -0500
Message-Id: <20190128155924.51521-166-sashal@kernel.org>
In-Reply-To: <20190128155924.51521-1-sashal@kernel.org>
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From: Arnaldo Carvalho de Melo <acme@redhat.com>

[ Upstream commit fca5085c15255bbde203b7322c15f07ebb12f63e ]

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@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.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@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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;
 }
-- 
2.19.1