irda: Fix parameter extraction stack overflow

Cc: stable@kernel.org
Reported-by: Ilja Van Sprundel <ivansprundel@ioactive.com>
Signed-off-by: Samuel Ortiz <samuel@sortiz.org>

net/irda/parameters.c

@@ -298,6 +298,8 @@ static int irda_extract_string(void *self, __u8 *buf, int len, __u8 pi,
 
 	p.pi = pi;     /* In case handler needs to know */
 	p.pl = buf[1]; /* Extract length of value */
+	if (p.pl > 32)
+		p.pl = 32;
 
 	IRDA_DEBUG(2, "%s(), pi=%#x, pl=%d\n", __func__,
 		   p.pi, p.pl);
@@ -318,7 +320,7 @@ static int irda_extract_string(void *self, __u8 *buf, int len, __u8 pi,
 		   (__u8) str[0], (__u8) str[1]);
 
 	/* Null terminate string */
-	str[p.pl+1] = '\0';
+	str[p.pl] = '\0';
 
 	p.pv.c = str; /* Handler will need to take a copy */