From 388e6fb3be63f88bc62ebda35ca0fc96e99ceed5 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 3 Jul 2025 20:27:15 +0200 Subject: [PATCH] avcodec/ffv1enc: Consider variation in slice sizes 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 --- libavcodec/ffv1enc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/libavcodec/ffv1enc.c b/libavcodec/ffv1enc.c index 97b38e4d16..8e5ebe773c 100644 --- a/libavcodec/ffv1enc.c +++ b/libavcodec/ffv1enc.c @@ -1684,9 +1684,11 @@ 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;