iSAC float decoder: Don't read past end of initialized part of buffer

webrtc/modules/audio_coding/codecs/isac/main/source/pitch_filter.c

Index: webrtc/modules/audio_coding/codecs/isac/main/source/pitch_filter.c
diff --git a/webrtc/modules/audio_coding/codecs/isac/main/source/pitch_filter.c b/webrtc/modules/audio_coding/codecs/isac/main/source/pitch_filter.c
index f03d230e65905df8e347a79bf379a5d86a9557fd..cdb30a74e708712d3e761be048078251efa7640c 100644
--- a/webrtc/modules/audio_coding/codecs/isac/main/source/pitch_filter.c
+++ b/webrtc/modules/audio_coding/codecs/isac/main/source/pitch_filter.c
@@ -16,6 +16,8 @@
 
 #include "os_specific_inline.h"
 
+#include "webrtc/system_wrappers/include/compile_assert_c.h"
+
 /*
  * We are implementing the following filters;
  *
@@ -275,6 +277,11 @@ static void FilterFrame(const double* in_data, PitchFiltstr* filter_state,
   /* Copy states to local variables. */
   memcpy(filter_parameters.buffer, filter_state->ubuf,
          sizeof(filter_state->ubuf));
+  COMPILE_ASSERT(sizeof(filter_parameters.buffer) >=
+                 sizeof(filter_state->ubuf));
+  memset(filter_parameters.buffer +
+             sizeof(filter_state->ubuf) / sizeof(filter_state->ubuf[0]),
+         0, sizeof(filter_parameters.buffer) - sizeof(filter_state->ubuf));
   memcpy(filter_parameters.damper_state, filter_state->ystate,
          sizeof(filter_state->ystate));