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* [PATCH] perf tools: Suppress potential format-truncation warning in util/pmu.c
@ 2018-11-11 18:45 Ben Hutchings
  2018-11-12 16:37 ` Arnaldo Carvalho de Melo
  2018-11-22  7:13 ` [tip:perf/core] perf pmu: Suppress potential format-truncation warning tip-bot for Ben Hutchings
  0 siblings, 2 replies; 3+ messages in thread
From: Ben Hutchings @ 2018-11-11 18:45 UTC (permalink / raw)
  To: Peter Zijlstra, Ingo Molnar, Arnaldo Carvalho de Melo
  Cc: Alexander Shishkin, Jiri Olsa, Namhyung Kim, linux-kernel

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Depending on which functions are inlined in util/pmu.c, the
snprintf() calls in perf_pmu__parse_{scale,unit,per_pkg,snapshot}()
might trigger a warning:

util/pmu.c: In function 'pmu_aliases':
util/pmu.c:178:31: error: '%s' directive output may be truncated writing up to 255 bytes into a region of size between 0 and 4095 [-Werror=format-truncation=]
  snprintf(path, PATH_MAX, "%s/%s.unit", dir, name);
                               ^~

I found this when trying to build perf from Linux 3.16 with gcc 8.
However I can reproduce the problem in mainline if I force
__perf_pmu__new_alias() to be inlined.

Suppress this by using scnprintf() as has been done elsewhere in
perf.

Cc: stable@vger.kernel.org
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
 tools/perf/util/pmu.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/tools/perf/util/pmu.c b/tools/perf/util/pmu.c
index 7799788f662f..25c7d2a4e91b 100644
--- a/tools/perf/util/pmu.c
+++ b/tools/perf/util/pmu.c
@@ -145,7 +145,7 @@ static int perf_pmu__parse_scale(struct perf_pmu_alias *alias, char *dir, char *
 	int fd, ret = -1;
 	char path[PATH_MAX];
 
-	snprintf(path, PATH_MAX, "%s/%s.scale", dir, name);
+	scnprintf(path, PATH_MAX, "%s/%s.scale", dir, name);
 
 	fd = open(path, O_RDONLY);
 	if (fd == -1)
@@ -175,7 +175,7 @@ static int perf_pmu__parse_unit(struct perf_pmu_alias *alias, char *dir, char *n
 	ssize_t sret;
 	int fd;
 
-	snprintf(path, PATH_MAX, "%s/%s.unit", dir, name);
+	scnprintf(path, PATH_MAX, "%s/%s.unit", dir, name);
 
 	fd = open(path, O_RDONLY);
 	if (fd == -1)
@@ -205,7 +205,7 @@ perf_pmu__parse_per_pkg(struct perf_pmu_alias *alias, char *dir, char *name)
 	char path[PATH_MAX];
 	int fd;
 
-	snprintf(path, PATH_MAX, "%s/%s.per-pkg", dir, name);
+	scnprintf(path, PATH_MAX, "%s/%s.per-pkg", dir, name);
 
 	fd = open(path, O_RDONLY);
 	if (fd == -1)
@@ -223,7 +223,7 @@ static int perf_pmu__parse_snapshot(struct perf_pmu_alias *alias,
 	char path[PATH_MAX];
 	int fd;
 
-	snprintf(path, PATH_MAX, "%s/%s.snapshot", dir, name);
+	scnprintf(path, PATH_MAX, "%s/%s.snapshot", dir, name);
 
 	fd = open(path, O_RDONLY);
 	if (fd == -1)

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2018-11-11 18:45 [PATCH] perf tools: Suppress potential format-truncation warning in util/pmu.c Ben Hutchings
2018-11-12 16:37 ` Arnaldo Carvalho de Melo
2018-11-22  7:13 ` [tip:perf/core] perf pmu: Suppress potential format-truncation warning tip-bot for Ben Hutchings

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