[PATCH 4.19 158/313] perf dso: Fix unchecked usage of strncpy()

From: Greg Kroah-Hartman
Date: Mon Feb 11 2019 - 10:41:38 EST

4.19-stable review patch. If anyone has any objections, please let me know.


[ 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@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Fixes: c9a8a6131fb6 ("perf tools: Move the temp file processing into decompress_kmodule")
Link: https://lkml.kernel.org/n/tip-tl2hdxj64tt4k8btbi6a0ugw@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
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,

if (pathname && (fd >= 0))
- strncpy(pathname, tmpbuf, len);
+ strlcpy(pathname, tmpbuf, len);

return fd;