avcodec/adpcm: XA: Check shift similar to filter

Fixes: negative shift
Fixes: 22499/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ADPCM_XA_fuzzer-5765452130418688

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 6d96bae9c4)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/adpcm.c

@@ -382,6 +382,10 @@ static int xa_decode(AVCodecContext *avctx, int16_t *out0, int16_t *out1,
             avpriv_request_sample(avctx, "unknown XA-ADPCM filter %d", filter);
             filter=0;
         }
+        if (shift < 0) {
+            avpriv_request_sample(avctx, "unknown XA-ADPCM shift %d", shift);
+            shift = 0;
+        }
         f0 = xa_adpcm_table[filter][0];
         f1 = xa_adpcm_table[filter][1];
 
@@ -407,10 +411,14 @@ static int xa_decode(AVCodecContext *avctx, int16_t *out0, int16_t *out1,
 
         shift  = 12 - (in[5+i*2] & 15);
         filter = in[5+i*2] >> 4;
-        if (filter >= FF_ARRAY_ELEMS(xa_adpcm_table)) {
+        if (filter >= FF_ARRAY_ELEMS(xa_adpcm_table) || shift < 0) {
             avpriv_request_sample(avctx, "unknown XA-ADPCM filter %d", filter);
             filter=0;
         }
+        if (shift < 0) {
+            avpriv_request_sample(avctx, "unknown XA-ADPCM shift %d", shift);
+            shift = 0;
+        }
 
         f0 = xa_adpcm_table[filter][0];
         f1 = xa_adpcm_table[filter][1];