avcodec/wavpack: Check L/R values before use to avoid harmless integer overflow and undefined behavior in fate

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 042260cde4)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/wavpack.c

@@ -472,6 +472,14 @@ static inline int wv_unpack_stereo(WavpackFrameContext *s, GetBitContext *gb,
                 s->decorr[i].samplesB[0] = L;
             }
         }
+
+        if (type == AV_SAMPLE_FMT_S16P) {
+            if (FFABS(L) + FFABS(R) > (1<<19)) {
+                av_log(s->avctx, AV_LOG_ERROR, "sample %d %d too large\n", L, R);
+                return AVERROR_INVALIDDATA;
+            }
+        }
+
         pos = (pos + 1) & 7;
         if (s->joint)
             L += (R -= (L >> 1));