avcodec/wmavoice: Check operations that can fail

There might be segfaults on failure.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
(cherry picked from commit e93875b756)

libavcodec/wmavoice.c

@@ -367,7 +367,7 @@ static av_cold void wmavoice_flush(AVCodecContext *ctx)
 static av_cold int wmavoice_decode_init(AVCodecContext *ctx)
 {
     static AVOnce init_static_once = AV_ONCE_INIT;
-    int n, flags, pitch_range, lsp16_flag;
+    int n, flags, pitch_range, lsp16_flag, ret;
     WMAVoiceContext *s = ctx->priv_data;
 
     ff_thread_once(&init_static_once, wmavoice_init_static_data);
@@ -395,10 +395,11 @@ static av_cold int wmavoice_decode_init(AVCodecContext *ctx)
     s->spillover_bitsize = 3 + av_ceil_log2(ctx->block_align);
     s->do_apf            =    flags & 0x1;
     if (s->do_apf) {
-        ff_rdft_init(&s->rdft,  7, DFT_R2C);
-        ff_rdft_init(&s->irdft, 7, IDFT_C2R);
-        ff_dct_init(&s->dct,  6, DCT_I);
-        ff_dct_init(&s->dst,  6, DST_I);
+        if ((ret = ff_rdft_init(&s->rdft,  7,  DFT_R2C)) < 0 ||
+            (ret = ff_rdft_init(&s->irdft, 7, IDFT_C2R)) < 0 ||
+            (ret = ff_dct_init (&s->dct,   6,    DCT_I)) < 0 ||
+            (ret = ff_dct_init (&s->dst,   6,    DST_I)) < 0)
+            return ret;
 
         ff_sine_window_init(s->cos, 256);
         memcpy(&s->sin[255], s->cos, 256 * sizeof(s->cos[0]));