Free DerBuffer in pem_to_der

Author: JeremiahM37

scripts/build_ffi.py

@@ -961,6 +961,7 @@ def build_ffi(local_wolfssl, features):
         int wc_PemToDer(const unsigned char* buff, long longSz, int type,
                         DerBuffer** pDer, void* heap, EncryptedInfo* info,
                         int* keyFormat);
+        void wc_FreeDer(DerBuffer** pDer);
         int wc_DerToPemEx(const byte* der, word32 derSz, byte* output, word32 outSz,
                         byte *cipher_info, int type);
         """

wolfcrypt/asn.py

@@ -42,7 +42,9 @@ def pem_to_der(pem, pem_type):
             err = "Error converting from PEM to DER. ({})".format(ret)
             raise WolfCryptError(err)
 
-        return _ffi.buffer(der[0][0].buffer, der[0][0].length)[:]
+        result = _ffi.buffer(der[0][0].buffer, der[0][0].length)[:]
+        _lib.wc_FreeDer(der)
+        return result
 
     def der_to_pem(der, pem_type):
         pem_length = _lib.wc_DerToPemEx(der, len(der), _ffi.NULL, 0, _ffi.NULL,