Zeroize temporary heap buffers used when deriving an ECC key

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index 54e497e..d959587 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -6389,7 +6389,7 @@
         status = mbedtls_to_psa_error(ret);
     }
     if (status != PSA_SUCCESS) {
-        mbedtls_free(*data);
+        mbedtls_zeroize_and_free(*data, m_bytes);
         *data = NULL;
     }
     mbedtls_mpi_free(&k);
@@ -6564,7 +6564,7 @@
     }
 
 exit:
-    mbedtls_free(data);
+    mbedtls_zeroize_and_free(data, bytes);
     return status;
 }