Fix QUIC crash when ProofSource::GetProof fails

net/quic/core/crypto/quic_crypto_server_config.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/quic/core/crypto/quic_crypto_server_config.h"
 
 #include <stdlib.h>
 
 #include <algorithm>
 #include <memory>
@@ skipping 1309 matching lines @@
         client_hello_state,
     std::unique_ptr<ValidateClientHelloResultCallback> done_cb) const {
   ValidateClientHelloHelper helper(client_hello_state, &done_cb);
   const CryptoHandshakeMessage& client_hello = client_hello_state->client_hello;
   ClientHelloInfo* info = &(client_hello_state->info);
 
   if (get_proof_failed) {
     info->reject_reasons.push_back(SERVER_CONFIG_UNKNOWN_CONFIG_FAILURE);
   }
 
-  if (!ValidateExpectedLeafCertificate(client_hello, *signed_config)) {
+  if (signed_config->chain != nullptr &&
+      !ValidateExpectedLeafCertificate(client_hello,
+                                       signed_config->chain->certs)) {
     info->reject_reasons.push_back(INVALID_EXPECTED_LEAF_CERTIFICATE);
   }
 
   if (info->client_nonce.size() != kNonceSize) {
     info->reject_reasons.push_back(CLIENT_NONCE_INVALID_FAILURE);
     // Invalid client nonce.
     LOG(ERROR) << "Invalid client nonce: " << client_hello.DebugString();
     DVLOG(1) << "Invalid client nonce.";
   }
 
@@ skipping 638 matching lines @@
   rand->RandBytes(&server_nonce[sizeof(timestamp)],
                   sizeof(server_nonce) - sizeof(timestamp));
 
   return server_nonce_boxer_.Box(
       rand,
       StringPiece(reinterpret_cast<char*>(server_nonce), sizeof(server_nonce)));
 }
 
 bool QuicCryptoServerConfig::ValidateExpectedLeafCertificate(
     const CryptoHandshakeMessage& client_hello,
-    const QuicSignedServerConfig& signed_config) const {
-  if (signed_config.chain->certs.empty()) {
+    const std::vector<string>& certs) const {
+  if (certs.empty()) {
     return false;
   }
 
   uint64_t hash_from_client;
   if (client_hello.GetUint64(kXLCT, &hash_from_client) != QUIC_NO_ERROR) {
     return false;
   }
-  return CryptoUtils::ComputeLeafCertHash(signed_config.chain->certs.at(0)) ==
-         hash_from_client;
+  return CryptoUtils::ComputeLeafCertHash(certs.at(0)) == hash_from_client;
 }
 
 bool QuicCryptoServerConfig::ClientDemandsX509Proof(
     const CryptoHandshakeMessage& client_hello) const {
   const QuicTag* their_proof_demands;
   size_t num_their_proof_demands;
 
   if (client_hello.GetTaglist(kPDMD, &their_proof_demands,
                               &num_their_proof_demands) != QUIC_NO_ERROR) {
     return false;
@@ skipping 15 matching lines @@
       expiry_time(QuicWallTime::Zero()),
       priority(0),
       source_address_token_boxer(nullptr) {}
 
 QuicCryptoServerConfig::Config::~Config() {}
 
 QuicSignedServerConfig::QuicSignedServerConfig() {}
 QuicSignedServerConfig::~QuicSignedServerConfig() {}
 
 }  // namespace net