linux-kernel - [PATCH 30/32] perf bench numa: Avoid possible truncation when using snprintf()

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Message-Id: <20170210013940.9998-31-acme@kernel.org>
Date:   Thu,  9 Feb 2017 22:39:38 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>
Cc:     linux-kernel@...r.kernel.org,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        David Ahern <dsahern@...il.com>, Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Petr Holasek <pholasek@...hat.com>,
        Wang Nan <wangnan0@...wei.com>
Subject: [PATCH 30/32] perf bench numa: Avoid possible truncation when using snprintf()

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

Addressing this warning from gcc 7:

    CC       /tmp/build/perf/bench/numa.o
  bench/numa.c: In function '__bench_numa':
  bench/numa.c:1582:42: error: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size between 8 and 17 [-Werror=format-truncation=]
       snprintf(tname, 32, "process%d:thread%d", p, t);
                                            ^~
  bench/numa.c:1582:25: note: directive argument in the range [0, 2147483647]
       snprintf(tname, 32, "process%d:thread%d", p, t);
                           ^~~~~~~~~~~~~~~~~~~~
  In file included from /usr/include/stdio.h:939:0,
                   from bench/../util/util.h:47,
                   from bench/../builtin.h:4,
                   from bench/numa.c:11:
  /usr/include/bits/stdio2.h:64:10: note: '__builtin___snprintf_chk' output between 17 and 35 bytes into a destination of size 32
     return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
          __bos (__s), __fmt, __va_arg_pack ());
          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  cc1: all warnings being treated as errors

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Petr Holasek <pholasek@...hat.com>
Cc: Wang Nan <wangnan0@...wei.com>
Link: http://lkml.kernel.org/n/tip-twa37vsfqcie5gwpqwnjuuz9@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/bench/numa.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/perf/bench/numa.c b/tools/perf/bench/numa.c
index 8efe904e486b..9e5a02d6b9a9 100644
--- a/tools/perf/bench/numa.c
+++ b/tools/perf/bench/numa.c
@@ -1573,13 +1573,13 @@ static int __bench_numa(const char *name)
 		"GB/sec,", "total-speed",	"GB/sec total speed");
 
 	if (g->p.show_details >= 2) {
-		char tname[32];
+		char tname[14 + 2 * 10 + 1];
 		struct thread_data *td;
 		for (p = 0; p < g->p.nr_proc; p++) {
 			for (t = 0; t < g->p.nr_threads; t++) {
-				memset(tname, 0, 32);
+				memset(tname, 0, sizeof(tname));
 				td = g->threads + p*g->p.nr_threads + t;
-				snprintf(tname, 32, "process%d:thread%d", p, t);
+				snprintf(tname, sizeof(tname), "process%d:thread%d", p, t);
 				print_res(tname, td->speed_gbs,
 					"GB/sec",	"thread-speed", "GB/sec/thread speed");
 				print_res(tname, td->system_time_ns / NSEC_PER_SEC,
-- 
2.9.3