Check X509Certificate::CreateFromHandle result.

net/tools/cert_verify_tool/verify_using_cert_verify_proc.cc

 // Copyright 2016 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/tools/cert_verify_tool/verify_using_cert_verify_proc.h"
 
 #include <iostream>
 
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_util.h"
@@ skipping 44 matching lines @@
 std::string SubjectFromX509Certificate(const net::X509Certificate* cert) {
   return cert->subject().GetDisplayName();
 }
 
 // Returns a textual representation of the Subject of |cert_handle|.
 std::string SubjectFromOSCertHandle(
     net::X509Certificate::OSCertHandle cert_handle) {
   scoped_refptr<net::X509Certificate> cert =
       net::X509Certificate::CreateFromHandle(
           cert_handle, net::X509Certificate::OSCertHandles());
+  if (!cert)
+    return std::string();
   return SubjectFromX509Certificate(cert.get());
 }
 
 void PrintCertStatus(int cert_status) {
   std::cout << base::StringPrintf("CertStatus: 0x%x\n", cert_status);
 
   for (const auto& flag : kCertStatusFlags) {
     if ((cert_status & flag.constant) == flag.constant)
       std::cout << " " << flag.name << "\n";
   }
@@ skipping 94 matching lines @@
   if (!dump_prefix_path.empty() && result.verified_cert) {
     if (!DumpX509CertificateChain(dump_prefix_path.AddExtension(
                                       FILE_PATH_LITERAL(".CertVerifyProc.pem")),
                                   result.verified_cert.get())) {
       return false;
     }
   }
 
   return rv == net::OK;
 }