[PATCH 3.16 42/99] perf parse-events: Fix unchecked usage of strncpy()

From: Ben Hutchings
Date: Tue Apr 02 2019 - 09:41:49 EST


3.16.65-rc1 review patch. If anyone has any objections, please let me know.

------------------

From: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>

commit bd8d57fb7e25e9fcf67a9eef5fa13aabe2016e07 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/parse-events.c: In function 'print_symbol_events':
util/parse-events.c:2465:4: error: 'strncpy' specified bound 100 equals destination size [-Werror=stringop-truncation]
strncpy(name, syms->symbol, MAX_NAME_LEN);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'print_symbol_events.constprop',
inlined from 'print_events' at util/parse-events.c:2508:2:
util/parse-events.c:2465:4: error: 'strncpy' specified bound 100 equals destination size [-Werror=stringop-truncation]
strncpy(name, syms->symbol, MAX_NAME_LEN);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'print_symbol_events.constprop',
inlined from 'print_events' at util/parse-events.c:2511:2:
util/parse-events.c:2465:4: error: 'strncpy' specified bound 100 equals destination size [-Werror=stringop-truncation]
strncpy(name, syms->symbol, MAX_NAME_LEN);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
cc1: all warnings being treated as errors

Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Fixes: 947b4ad1d198 ("perf list: Fix max event string size")
Link: https://lkml.kernel.org/n/tip-b663e33bm6x8hrkie4uxh7u2@xxxxxxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
tools/perf/util/parse-events.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1217,7 +1217,7 @@ static void print_symbol_events(const ch
if (strlen(syms->alias))
snprintf(name, MAX_NAME_LEN, "%s OR %s", syms->symbol, syms->alias);
else
- strncpy(name, syms->symbol, MAX_NAME_LEN);
+ strlcpy(name, syms->symbol, MAX_NAME_LEN);

printf(" %-50s [%s]\n", name, event_type_descriptors[type]);