avcodec/agm: YUV420 without DCT needs even dimensions

Fixes: out of array access
Fixes: 19892/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AGM_fuzzer-5707525924323328
Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

diff --git a/libavcodec/agm.c b/libavcodec/agm.c
index c5c9a88dd9081653bfb3800110ea915052db0e96..bc9dfc02f310af07d236063d3510d4023bf33e93 100644 (file)
--- a/libavcodec/agm.c
+++ b/libavcodec/agm.c
@@ -1242,6 +1242,11 @@ static av_cold int decode_init(AVCodecContext *avctx)
     s->dct = avctx->codec_tag != MKTAG('A', 'G', 'M', '4') &&
              avctx->codec_tag != MKTAG('A', 'G', 'M', '5');
 
+    if (!s->rgb && !s->dct) {
+        if ((avctx->width & 1) || (avctx->height & 1))
+            return AVERROR_INVALIDDATA;
+    }
+
     avctx->idct_algo = FF_IDCT_SIMPLE;
     ff_idctdsp_init(&s->idsp, avctx);
     ff_init_scantable(s->idsp.idct_permutation, &s->scantable, ff_zigzag_direct);