wmapro: check the min_samples_per_subframe

Must be at least WMAPRO_BLOCK_MIN_SIZE.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org

libavcodec/wmaprodec.c

@@ -106,6 +106,7 @@
 
 #define WMAPRO_BLOCK_MIN_BITS  6                                           ///< log2 of min block size
 #define WMAPRO_BLOCK_MAX_BITS 13                                           ///< log2 of max block size
+#define WMAPRO_BLOCK_MIN_SIZE (1 << WMAPRO_BLOCK_MIN_BITS)                 ///< minimum block size
 #define WMAPRO_BLOCK_MAX_SIZE (1 << WMAPRO_BLOCK_MAX_BITS)                 ///< maximum block size
 #define WMAPRO_BLOCK_SIZES    (WMAPRO_BLOCK_MAX_BITS - WMAPRO_BLOCK_MIN_BITS + 1) ///< possible block sizes
 
@@ -336,6 +337,12 @@ static av_cold int decode_init(AVCodecContext *avctx)
         return AVERROR_INVALIDDATA;
     }
 
+    if (s->min_samples_per_subframe < WMAPRO_BLOCK_MIN_SIZE) {
+        av_log(avctx, AV_LOG_ERROR, "Invalid minimum block size %i\n",
+               s->max_num_subframes);
+        return AVERROR_INVALIDDATA;
+    }
+
     if (s->avctx->sample_rate <= 0) {
         av_log(avctx, AV_LOG_ERROR, "invalid sample rate\n");
         return AVERROR_INVALIDDATA;