Avoid integer overflow errors when parsing Exp-Golomb codes

media/filters/h264_bit_reader.cc

 // Copyright 2014 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 "base/logging.h"
 #include "media/filters/h264_bit_reader.h"
 
 namespace media {
 
 H264BitReader::H264BitReader()
@@ skipping 61 matching lines @@
   while (num_remaining_bits_in_curr_byte_ < bits_left) {
     // Take all that's left in current byte, shift to make space for the rest.
     *out |= (curr_byte_ << (bits_left - num_remaining_bits_in_curr_byte_));
     bits_left -= num_remaining_bits_in_curr_byte_;
 
     if (!UpdateCurrByte())
       return false;
   }
 
   *out |= (curr_byte_ >> (num_remaining_bits_in_curr_byte_ - bits_left));
-  *out &= ((1 << num_bits) - 1);
+  *out &= ((1u << num_bits) - 1);

[sandersd (OOO until July 31), 2016/04/07 20:48:09]

Both should be 1u.

[jrummell, 2016/04/07 21:13:59]

Done.

   num_remaining_bits_in_curr_byte_ -= bits_left;
 
   return true;
 }
 
 off_t H264BitReader::NumBitsLeft() {
   return (num_remaining_bits_in_curr_byte_ + bytes_left_ * 8);
 }
 
 bool H264BitReader::HasMoreRBSPData() {
@@ skipping 20 matching lines @@
 
   bytes_left_ = 0;
   return false;
 }
 
 size_t H264BitReader::NumEmulationPreventionBytesRead() {
   return emulation_prevention_bytes_;
 }
 
 }  // namespace media