[FFmpeg-cvslog] avcodec/magicyuv: Check that there are enough lines for interlacing to be possible

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Sat Feb 22 00:42:30 2020 +0100| [f8a0e9f9f71cf5650bdc250ff7475e0f7d8e8420] | committer: Michael Niedermayer

avcodec/magicyuv: Check that there are enough lines for interlacing to be possible

Fixes: out of array access
Fixes: 20763/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MAGICYUV_fuzzer-5759562508664832

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Paul B Mahol <onemda at gmail.com>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=f8a0e9f9f71cf5650bdc250ff7475e0f7d8e8420
---

 libavcodec/magicyuv.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/libavcodec/magicyuv.c b/libavcodec/magicyuv.c
index 21a32785bc..aacd0d4d7d 100644
--- a/libavcodec/magicyuv.c
+++ b/libavcodec/magicyuv.c
@@ -659,6 +659,17 @@ static int magy_decode_frame(AVCodecContext *avctx, void *data,
         return AVERROR_INVALIDDATA;
     }
 
+    if (s->interlaced) {
+        if ((s->slice_height >> s->vshift[1]) < 2) {
+            av_log(avctx, AV_LOG_ERROR, "impossible slice height\n");
+            return AVERROR_INVALIDDATA;
+        }
+        if ((avctx->coded_height % s->slice_height) && ((avctx->coded_height % s->slice_height) >> s->vshift[1]) < 2) {
+            av_log(avctx, AV_LOG_ERROR, "impossible height\n");
+            return AVERROR_INVALIDDATA;
+        }
+    }
+
     for (i = 0; i < s->planes; i++) {
         av_fast_malloc(&s->slices[i], &s->slices_size[i], s->nb_slices * sizeof(Slice));
         if (!s->slices[i])