Handle failing cases of DH allocation

src/common/tortls.c

@@ -808,6 +808,7 @@ tor_tls_context_new(crypto_pk_env_t *identity, unsigned int key_lifetime)
     goto error;
   {
     crypto_dh_env_t *dh = crypto_dh_new(DH_TYPE_TLS);
+    tor_assert(dh);
     SSL_CTX_set_tmp_dh(result->ctx, _crypto_dh_env_get_dh(dh));
     crypto_dh_free(dh);
   }

src/or/onion.c

@@ -259,6 +259,10 @@ onion_skin_server_handshake(const char *onion_skin, /*ONIONSKIN_CHALLENGE_LEN*/
   }
 
   dh = crypto_dh_new(DH_TYPE_CIRCUIT);
+  if (!dh) {
+    log_warn(LD_BUG, "Couldn't allocate DH key");
+    goto err;
+  }
   if (crypto_dh_get_public(dh, handshake_reply_out, DH_KEY_LEN)) {
     log_info(LD_GENERAL, "crypto_dh_get_public failed.");
     goto err;