[PATCH 4.14 03/43] perf header: Fix unchecked usage of strncpy()

Greg Kroah-Hartman
2019-07-02T08:10:26Z

From: Arnaldo Carvalho de Melo <acme@redhat.com>

commit 5192bde7d98c99f2cd80225649e3c2e7493722f7 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
tools/perf/util/header.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3171,7 +3171,7 @@ perf_event__synthesize_event_update_name
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;