From: Michael Niedermayer <michael@niedermayer.cc>
Date: Fri, 21 Feb 2020 23:42:30 +0000 (+0100)
Subject: avcodec/magicyuv: Check that there are enough lines for interlacing to be possible
X-Git-Url: https://git.sesse.net/?a=commitdiff_plain;h=f8a0e9f9f71cf5650bdc250ff7475e0f7d8e8420;p=ffmpeg

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@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---

diff --git a/libavcodec/magicyuv.c b/libavcodec/magicyuv.c
index 21a32785bc8..aacd0d4d7dc 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])