WebRtcIlbcfix_Smooth: Fix UBSan fuzzer bug (left shift of 1 by 31 overflows)

webrtc/modules/audio_coding/codecs/ilbc/smooth.c

 /*
  *  Copyright (c) 2011 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 150 matching lines @@
         /* num in Q34 */
         num=ENH_A0_MINUS_A0A0DIV4;
       }
 
       /* A sqrt( (ENH_A0-(ENH_A0^2)/4)*(w00*w00)/(w11*w00 + w10*w10) ) in Q9 */
       A = (int16_t)WebRtcSpl_SqrtFloor(WebRtcSpl_DivW32W16(num, denomW16));
 
       /* B_W32 is in Q30 ( B = 1 - ENH_A0/2 - A * w10/w00 ) */
       scale1 = 31-bitsw10;
       scale2 = 21-scale1;
-      w10prim = w10 * (1 << scale1);
+      w10prim = w10 == 0 ? 0 : w10 * (1 << scale1);
       w00prim = WEBRTC_SPL_SHIFT_W32(w00, -scale2);
       scale = bitsw00-scale2-15;
 
       if (scale>0) {
         w10prim >>= scale;
         w00prim >>= scale;
       }
 
       if ((w00prim>0)&&(w10prim>0)) {
         w11_div_w00=WebRtcSpl_DivW32W16(w10prim, (int16_t)w00prim);
@@ skipping 19 matching lines @@
     }
 
     /* create smoothed sequence */
 
     WebRtcSpl_ScaleAndAddVectors(surround, A, 9,
                                 current, B, 14,
                                 odata, ENH_BLOCKL);
   }
   return;
 }