[FFmpeg-devel] [PATCH 08/10] avcodec/ffv1enc: Consider variation in slice sizes

[Michael Niedermayer <michael@niedermayer.cc>]

When splitting a 5 lines image in 2 slices one will be 3 lines and thus need more space

Fixes: Assertion sc->slice_coding_mode == 0 failed at libavcodec/ffv1enc.c:1668
Fixes: 422811239/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FFV1_fuzzer-4933405139861504

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/ffv1enc.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/libavcodec/ffv1enc.c b/libavcodec/ffv1enc.c
index 463f46e091e..ad72906466d 100644
--- a/libavcodec/ffv1enc.c
+++ b/libavcodec/ffv1enc.c
@@ -1679,9 +1679,11 @@ size_t ff_ffv1_encode_buffer_size(AVCodecContext *avctx)
 {
     FFV1Context *f = avctx->priv_data;
 
-    size_t maxsize = avctx->width*avctx->height * (1 + f->transparency);
+    int w = avctx->width  + f->num_h_slices;
+    int h = avctx->height + f->num_v_slices;
+    size_t maxsize = w*h * (1 + f->transparency);
     if (f->chroma_planes)
-        maxsize += AV_CEIL_RSHIFT(avctx->width, f->chroma_h_shift) * AV_CEIL_RSHIFT(f->height, f->chroma_v_shift) * 2;
+        maxsize += AV_CEIL_RSHIFT(w, f->chroma_h_shift) * AV_CEIL_RSHIFT(h, f->chroma_v_shift) * 2;
     maxsize += f->slice_count * 800; //for slice header
     if (f->version > 3) {
         maxsize *= f->bits_per_raw_sample + 1;
-- 
2.49.0

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