Make string_util::WriteInto() DCHECK() that the supplied |length_with_null| > 1, meaning that the...

crypto/encryptor_win.cc

 // Copyright (c) 2011 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 "crypto/encryptor.h"
 
 #include <string.h>
 
 #include "base/string_util.h"
 #include "crypto/symmetric_key.h"
@@ skipping 65 matching lines @@
                         reinterpret_cast<BYTE*>(&padding_method), 0);
   if (!ok)
     return false;
 
   return true;
 }
 
 bool Encryptor::Encrypt(const base::StringPiece& plaintext,
                         std::string* ciphertext) {
   DWORD data_len = plaintext.size();
+  CHECK((data_len > 0u) || (mode_ == CBC));
   DWORD total_len = data_len + block_size_;
-  CHECK_GT(total_len, data_len);
+  CHECK_GT(total_len, 0u);
+  CHECK_GT(total_len + 1, data_len);
 
   // CryptoAPI encrypts/decrypts in place.
   char* ciphertext_data = WriteInto(ciphertext, total_len + 1);
   memcpy(ciphertext_data, plaintext.data(), data_len);
 
   BOOL ok = CryptEncrypt(capi_key_.get(), NULL, TRUE, 0,
                          reinterpret_cast<BYTE*>(ciphertext_data), &data_len,
                          total_len);
   if (!ok) {
     ciphertext->clear();
     return false;
   }
 
   ciphertext->resize(data_len);
   return true;
 }
 
 bool Encryptor::Decrypt(const base::StringPiece& ciphertext,
                         std::string* plaintext) {
   DWORD data_len = ciphertext.size();
-  if (data_len == 0 || (data_len + 1) < data_len)
-    return false;
+  CHECK_GT(data_len, 0u);
+  CHECK_GT(data_len + 1, data_len);
 
   // CryptoAPI encrypts/decrypts in place.
   char* plaintext_data = WriteInto(plaintext, data_len + 1);
   memcpy(plaintext_data, ciphertext.data(), data_len);
 
   BOOL ok = CryptDecrypt(capi_key_.get(), NULL, TRUE, 0,
                          reinterpret_cast<BYTE*>(plaintext_data), &data_len);
   if (!ok) {
     plaintext->clear();
     return false;
   }
 
   plaintext->resize(data_len);
   return true;
 }
 
 }  // namespace crypto