[FFmpeg-cvslog] avcodec/vc1dec: Clear mb_type_base and ttblk_base

[Michael Niedermayer]

ffmpeg | branch: release/4.3 | Michael Niedermayer <michael at niedermayer.cc> | Sun Aug  4 22:15:08 2024 +0200| [9b7d4ad167708ef5db038eed72370333d55c8b28] | committer: Michael Niedermayer

avcodec/vc1dec: Clear mb_type_base and ttblk_base

Fixes: two use-of-uninitialized-value
Fixes: 70856/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VC1IMAGE_fuzzer-5539349918187520

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit 50471f96c4a68874575ab21f799c5999ed920838)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9b7d4ad167708ef5db038eed72370333d55c8b28
---

 libavcodec/vc1dec.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavcodec/vc1dec.c b/libavcodec/vc1dec.c
index 01ca8ea389..a7f46a2246 100644
--- a/libavcodec/vc1dec.c
+++ b/libavcodec/vc1dec.c
@@ -344,7 +344,7 @@ av_cold int ff_vc1_decode_init_alloc_tables(VC1Context *v)
     if (!v->block || !v->cbp_base)
         goto error;
     v->cbp              = v->cbp_base + 2 * s->mb_stride;
-    v->ttblk_base       = av_malloc(sizeof(v->ttblk_base[0]) * 3 * s->mb_stride);
+    v->ttblk_base       = av_mallocz(sizeof(v->ttblk_base[0]) * 3 * s->mb_stride);
     if (!v->ttblk_base)
         goto error;
     v->ttblk            = v->ttblk_base + 2 * s->mb_stride;
@@ -358,7 +358,7 @@ av_cold int ff_vc1_decode_init_alloc_tables(VC1Context *v)
     v->luma_mv          = v->luma_mv_base + 2 * s->mb_stride;
 
     /* allocate block type info in that way so it could be used with s->block_index[] */
-    v->mb_type_base = av_malloc(s->b8_stride * (mb_height * 2 + 1) + s->mb_stride * (mb_height + 1) * 2);
+    v->mb_type_base = av_mallocz(s->b8_stride * (mb_height * 2 + 1) + s->mb_stride * (mb_height + 1) * 2);
     if (!v->mb_type_base)
         goto error;
     v->mb_type[0]   = v->mb_type_base + s->b8_stride + 1;