dr_42: add boundary checking

src/descriptors/dr_42.c

@@ -65,6 +65,9 @@ dvbpsi_stuffing_dr_t * dvbpsi_DecodeStuffingDr(
 
     /* Decode data */
     p_decoded->i_stuffing_length = p_descriptor->i_length;
+    if (p_decoded->i_stuffing_length > 255)
+        p_decoded->i_stuffing_length = 255;
+
     if (p_decoded->i_stuffing_length)
         memcpy(p_decoded->i_stuffing_byte,
                p_descriptor->p_data,
@@ -82,6 +85,9 @@ dvbpsi_stuffing_dr_t * dvbpsi_DecodeStuffingDr(
 dvbpsi_descriptor_t * dvbpsi_GenStuffingDr(dvbpsi_stuffing_dr_t * p_decoded,
                                            bool b_duplicate)
 {
+    if (p_decoded->i_stuffing_length > 255)
+        p_decoded->i_stuffing_length = 255;
+
     /* Create the descriptor */
     dvbpsi_descriptor_t * p_descriptor =
             dvbpsi_NewDescriptor(0x42, p_decoded->i_stuffing_length, NULL);