From b849ac006b667dbd494a28de2f8b059fec308ac2 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Sun, 13 Jul 2025 01:17:02 +0200 Subject: [PATCH] avcodec/mpegvideo_dec: Fix lowres=3 field select interlaced mpeg4 frame Fixes: out of array read in the chroma plane Fixes: 428034092/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG4_DEC_fuzzer-5582608941776896.test Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavcodec/mpegvideo_dec.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/libavcodec/mpegvideo_dec.c b/libavcodec/mpegvideo_dec.c index 4a54f6cd61..85e24c667e 100644 --- a/libavcodec/mpegvideo_dec.c +++ b/libavcodec/mpegvideo_dec.c @@ -557,7 +557,7 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s, ptr_cr = ref_picture[2] + uvsrc_y * uvlinesize + uvsrc_x; if ((unsigned) src_x > FFMAX( h_edge_pos - (!!sx) - 2 * block_s, 0) || uvsrc_y<0 || - (unsigned) src_y > FFMAX((v_edge_pos >> field_based) - (!!sy) - FFMAX(h, hc<chroma_y_shift), 0)) { + (unsigned) src_y > FFMAX((v_edge_pos >> field_based) - (!!sy) - FFMAX(h, field_select + hc<chroma_y_shift), 0)) { s->vdsp.emulated_edge_mc(s->sc.edge_emu_buffer, ptr_y, linesize >> field_based, linesize >> field_based, 17, 17 + field_based,