Fix for integer overflow in NetEq.

webrtc/modules/audio_coding/neteq/expand.cc

 /*
  *  Copyright (c) 2012 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 663 matching lines @@
                               unvoiced_vector,
                               parameters.ar_filter,
                               kUnvoicedLpcOrder + 1,
                               128);
     int16_t unvoiced_prescale;
     if (WebRtcSpl_MaxAbsValueW16(unvoiced_vector, 128) > 4000) {
       unvoiced_prescale = 4;
     } else {
       unvoiced_prescale = 0;
     }
-    int32_t unvoiced_energy = WebRtcSpl_DotProductWithScale(unvoiced_vector,
-                                                            unvoiced_vector,
-                                                            128,
-                                                            unvoiced_prescale);
+    int32_t unvoiced_energy = WebRtcSpl_DotProductWithScale_64b(

[hlundin-webrtc, 2016/12/12 21:40:41]

Will you not end up with the same overflow problem when casting the results to
int32_t?

[ivoc, 2016/12/13 08:43:09]

Oops, good catch, I'll change this to int64_t.

[kwiberg-webrtc, 2016/12/13 08:45:36]

I would imagine so. Since all the partial sums are positive, you can't have
overflow in an intermediate value without also having overflow in the final sum.

+        unvoiced_vector, unvoiced_vector, 128, unvoiced_prescale);
 
     // Normalize |unvoiced_energy| to 28 or 29 bits to preserve sqrt() accuracy.
     int16_t unvoiced_scale = WebRtcSpl_NormW32(unvoiced_energy) - 3;
     // Make sure we do an odd number of shifts since we already have 7 shifts
     // from dividing with 128 earlier. This will make the total scale factor
     // even, which is suitable for the sqrt.
     unvoiced_scale += ((unvoiced_scale & 0x1) ^ 0x1);
     unvoiced_energy = WEBRTC_SPL_SHIFT_W32(unvoiced_energy, unvoiced_scale);
     int16_t unvoiced_gain =
         static_cast<int16_t>(WebRtcSpl_SqrtFloor(unvoiced_energy));
@@ skipping 263 matching lines @@
   const size_t kMaxRandSamples = RandomVector::kRandomTableSize;
   while (samples_generated < length) {
     size_t rand_length = std::min(length - samples_generated, kMaxRandSamples);
     random_vector_->IncreaseSeedIncrement(seed_increment);
     random_vector_->Generate(rand_length, &random_vector[samples_generated]);
     samples_generated += rand_length;
   }
 }
 
 }  // namespace webrtc