avcodec/wavpack: Check rate_x and sample rate for overflow

Fixes: shift exponent 32 is too large for 32-bit type 'int'
Fixes: 21647/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WAVPACK_fuzzer-5686168323883008

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: David Bryant <david@wavpack.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/wavpack.c

@@ -1359,7 +1359,10 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
                 bytestream2_skip(&gb, ssize);
                 continue;
             }
-            rate_x = 1 << bytestream2_get_byte(&gb);
+            rate_x = bytestream2_get_byte(&gb);
+            if (rate_x > 30)
+                return AVERROR_INVALIDDATA;
+            rate_x = 1 << rate_x;
             dsd_mode = bytestream2_get_byte(&gb);
             if (dsd_mode && dsd_mode != 1 && dsd_mode != 3) {
                 av_log(avctx, AV_LOG_ERROR, "Invalid DSD encoding mode: %d\n",
@@ -1498,9 +1501,13 @@ static int wavpack_decode_block(AVCodecContext *avctx, int block_no,
                 av_log(avctx, AV_LOG_ERROR, "Custom sample rate missing.\n");
                 return AVERROR_INVALIDDATA;
             }
-            new_samplerate = sample_rate * rate_x;
+            new_samplerate = sample_rate;
         } else
-            new_samplerate = wv_rates[sr] * rate_x;
+            new_samplerate = wv_rates[sr];
+
+        if (new_samplerate * (uint64_t)rate_x > INT_MAX)
+            return AVERROR_INVALIDDATA;
+        new_samplerate *= rate_x;
 
         if (multiblock) {
             if (chan)