Make wpa_config_read_blob() easier for static analyzers

While encoded == NULL could happen in the case of an empty blob, that
will result in encoded_len == 0 and base64_decode() not derefencing the
src argument. That seems to be too difficult for some static analyzers,
so to avoid false warnings, explicitly reject the encoded == NULL case
without even trying to base64 decode it. (CID 164709)

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>

wpa_supplicant/config_file.c

@@ -312,7 +312,7 @@ static struct wpa_config_blob * wpa_config_read_blob(FILE *f, int *line,
 		encoded_len += len;
 	}
 
-	if (!end) {
+	if (!end || !encoded) {
 		wpa_printf(MSG_ERROR, "Line %d: blob was not terminated "
 			   "properly", *line);
 		os_free(encoded);