Added boundary check for array access as a short-term way of fixing the bug of out-of-bounds reads …

webrtc/modules/audio_processing/aec/aec_core.c

 /*
  *  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 802 matching lines @@
   for (i = 0; i < kHistorySizeBlocks; i++) {
     l1_norm += abs(i - median) * self->delay_histogram[i];
   }
   self->delay_std = (int)((l1_norm + self->num_delay_values / 2) /
       self->num_delay_values) * kMsPerBlock;
 
   // Determine fraction of delays that are out of bounds, that is, either
   // negative (anti-causal system) or larger than the AEC filter length.
   {
     int num_delays_out_of_bounds = self->num_delay_values;
-    for (i = lookahead; i < lookahead + self->num_partitions; ++i) {
-      num_delays_out_of_bounds -= self->delay_histogram[i];
+    const int histogram_length = sizeof(self->delay_histogram) /
+      sizeof(self->delay_histogram[0]);
+    for (i = lookahead;
+         ((i < lookahead + self->num_partitions) && (i < histogram_length));

[hlundin-webrtc, 2015/09/14 07:34:48]

You don't need the outer parentheses, and I don't think they improve
readability.

[peah-webrtc, 2015/09/14 07:56:07]

Acknowledged.

+         ++i) {
+        num_delays_out_of_bounds -= self->delay_histogram[i];
     }
     self->fraction_poor_delays = (float)num_delays_out_of_bounds /
         self->num_delay_values;
   }
 
   // Reset histogram.
   memset(self->delay_histogram, 0, sizeof(self->delay_histogram));
   self->num_delay_values = 0;
 
   return;
@@ skipping 1082 matching lines @@
 int WebRtcAec_extended_filter_enabled(AecCore* self) {
   return self->extended_filter_enabled;
 }
 
 int WebRtcAec_system_delay(AecCore* self) { return self->system_delay; }
 
 void WebRtcAec_SetSystemDelay(AecCore* self, int delay) {
   assert(delay >= 0);
   self->system_delay = delay;
 }