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Subject[tip:perf/core] perf header: Fix unchecked usage of strncpy()
Commit-ID:  7473d42ba08f9ed4c1d7a8e72e2ad1fcd0135155
Gitweb: https://git.kernel.org/tip/7473d42ba08f9ed4c1d7a8e72e2ad1fcd0135155
Author: Arnaldo Carvalho de Melo <acme@redhat.com>
AuthorDate: Thu, 6 Dec 2018 11:02:57 -0300
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Thu, 6 Dec 2018 16:39:15 -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_unit':
util/header.c:3586:2: error: 'strncpy' output truncated before terminating nul copying as many bytes from a string as its length [-Werror=stringop-truncation]
strncpy(ev->data, evsel->unit, size);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
util/header.c:3579:16: note: length computed here
size_t size = strlen(evsel->unit);
^~~~~~~~~~~~~~~~~~~

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-fiikh5nay70bv4zskw2aa858@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 4a64739c67e7..c87cfe6b7c96 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -3583,7 +3583,7 @@ perf_event__synthesize_event_update_unit(struct perf_tool *tool,
if (ev == NULL)
return -ENOMEM;

- strncpy(ev->data, evsel->unit, size);
+ strlcpy(ev->data, evsel->unit, size + 1);
err = process(tool, (union perf_event *)ev, NULL, NULL);
free(ev);
return err;
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