avcodec/wavarc: Check k

Fixes: Assertion failure
Fixes: 55849/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_WAVARC_fuzzer-6590105973555200

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

libavcodec/wavarc.c

@@ -192,6 +192,8 @@ static int decode_1dif(AVCodecContext *avctx,
         if (block_type < 4 && block_type >= 0) {
             k = 1 + (avctx->sample_fmt == AV_SAMPLE_FMT_S16P);
             k = get_urice(gb, k) + 1;
+            if (k > 32)
+                return AVERROR_INVALIDDATA;
         }
 
         switch (block_type) {
@@ -282,6 +284,8 @@ static int decode_2slp(AVCodecContext *avctx,
         if (block_type < 5 && block_type >= 0) {
             k = 1 + (avctx->sample_fmt == AV_SAMPLE_FMT_S16P);
             k = get_urice(gb, k) + 1;
+            if (k > 32)
+                return AVERROR_INVALIDDATA;
         }
 
         switch (block_type) {