avcodec/bink: disallow odd positioned scaled blocks

Fixes: out of array access
Fixes: 47911/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_BINK_fuzzer-6194020855971840

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg


Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit b14104a6)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/bink.c

@@ -1054,7 +1054,7 @@ static int bink_decode_plane(BinkContext *c, AVFrame *frame, GetBitContext *gb,
         for (bx = 0; bx < bw; bx++, dst += 8, prev += 8) {
             blk = get_value(c, BINK_SRC_BLOCK_TYPES);
             // 16x16 block type on odd line means part of the already decoded block, so skip it
-            if ((by & 1) && blk == SCALED_BLOCK) {
+            if (((by & 1) || (bx & 1)) && blk == SCALED_BLOCK) {
                 bx++;
                 dst  += 8;
                 prev += 8;