Utils: Change sprintf to snprintf

Using sprintf can cause segmentation fault by exceeding the size of buffer array.

Signed-off-by: Mateusz Kusiak <mateusz.kusiak@intel.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>

util.c

diff --git a/util.c b/util.c
index cdf1da2..ea07277 100644
--- a/util.c
+++ b/util.c
@@ -947,12 +947,12 @@
 	/* First look in /sys/block/$DEVNM/dev for %d:%d
 	 * If that fails, try parsing out a number
 	 */
-	char path[100];
+	char path[PATH_MAX];
 	char *ep;
 	int fd;
 	int mjr,mnr;
 
-	sprintf(path, "/sys/block/%s/dev", devnm);
+	snprintf(path, sizeof(path), "/sys/block/%s/dev", devnm);
 	fd = open(path, O_RDONLY);
 	if (fd >= 0) {
 		char buf[20];