Clear wpa_supplicant configuration keys explicitly

Use an explicit memset call to clear any wpa_supplicant configuration
parameter that contains private information like keys or identity. This
brings in an additional layer of protection by reducing the length of
time this type of private data is kept in memory.

Signed-off-by: Jouni Malinen <j@w1.fi>

src/utils/common.c

@@ -827,3 +827,22 @@ void int_array_add_unique(int **res, int a)
 
 	*res = n;
 }
+
+
+void str_clear_free(char *str)
+{
+	if (str) {
+		size_t len = os_strlen(str);
+		os_memset(str, 0, len);
+		os_free(str);
+	}
+}
+
+
+void bin_clear_free(void *bin, size_t len)
+{
+	if (bin) {
+		os_memset(bin, 0, len);
+		os_free(bin);
+	}
+}