[tip:perf/core] perf tests: Do not assume that readlink() returns a null terminated string

[tip-bot for Tommi Rantala <tipbot@zytor.com>]

Commit-ID:  0e6ba11511aef91ba8e2528ddc681d88922d7b0b
Gitweb:     http://git.kernel.org/tip/0e6ba11511aef91ba8e2528ddc681d88922d7b0b
Author:     Tommi Rantala <tommi.t.rantala@nokia.com>
AuthorDate: Wed, 22 Mar 2017 15:06:21 +0200
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 27 Mar 2017 15:35:56 -0300

perf tests: Do not assume that readlink() returns a null terminated string

Ensure that the string in buf is null terminated.

Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20170322130624.21881-4-tommi.t.rantala@nokia.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/tests/sdt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/tests/sdt.c b/tools/perf/tests/sdt.c
index f59d210..26e5b7a 100644
--- a/tools/perf/tests/sdt.c
+++ b/tools/perf/tests/sdt.c
@@ -43,7 +43,7 @@ static char *get_self_path(void)
 {
 	char *buf = calloc(PATH_MAX, sizeof(char));
 
-	if (buf && readlink("/proc/self/exe", buf, PATH_MAX) < 0) {
+	if (buf && readlink("/proc/self/exe", buf, PATH_MAX - 1) < 0) {
 		pr_debug("Failed to get correct path of perf\n");
 		free(buf);
 		return NULL;