avcodec/wavarc: Check shift

Fixes: shift exponent 1285 is too large for 32-bit type 'int'
Fixes: 60870/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WAVARC_fuzzer-5332050340347904

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 1a81a40de2)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/wavarc.c

@@ -205,6 +205,10 @@ static int decode_1dif(AVCodecContext *avctx,
             continue;
         case 6:
             s->shift = get_urice(gb, 2);
+            if ((unsigned)s->shift > 31) {
+                s->shift = 0;
+                return AVERROR_INVALIDDATA;
+            }
             continue;
         case 5:
             if (avctx->sample_fmt == AV_SAMPLE_FMT_U8P) {
@@ -301,6 +305,10 @@ static int decode_2slp(AVCodecContext *avctx,
             continue;
         case 7:
             s->shift = get_urice(gb, 2);
+            if ((unsigned)s->shift > 31) {
+                s->shift = 0;
+                return AVERROR_INVALIDDATA;
+            }
             continue;
         case 6:
             if (avctx->sample_fmt == AV_SAMPLE_FMT_U8P) {