smacker: check the return value of smacker_decode_tree

Also prevent a memory leak.

Reported-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

libavcodec/smacker.c

@@ -629,7 +629,16 @@ static int smka_decode_frame(AVCodecContext *avctx, void *data,
         h[i].lengths = av_mallocz(256 * sizeof(int));
         h[i].values = av_mallocz(256 * sizeof(int));
         skip_bits1(&gb);
-        smacker_decode_tree(&gb, &h[i], 0, 0);
+        if (smacker_decode_tree(&gb, &h[i], 0, 0) < 0) {
+            for (; i >= 0; i--) {
+                if (vlc[i].table)
+                    ff_free_vlc(&vlc[i]);
+                av_free(h[i].bits);
+                av_free(h[i].lengths);
+                av_free(h[i].values);
+            }
+            return AVERROR_INVALIDDATA;
+        }
         skip_bits1(&gb);
         if(h[i].current > 1) {
             res = init_vlc(&vlc[i], SMKTREE_BITS, h[i].length,