From d7d3f1af2ab23cae1b2fc36afafc9872bc633808 Mon Sep 17 00:00:00 2001 From: Michael Niedermayer Date: Thu, 8 Jun 2023 15:47:37 +0200 Subject: [PATCH] avcodec/mpegvideo_dec: consider interlaced lowres 4:2:0 chroma in edge emulation check better Fixes: out of array read Fixes: 59673/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MPEG1VIDEO_fuzzer-5194311374077952 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavcodec/mpegvideo_dec.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/libavcodec/mpegvideo_dec.c b/libavcodec/mpegvideo_dec.c index 765ccd0ba4..c87ca77ae6 100644 --- a/libavcodec/mpegvideo_dec.c +++ b/libavcodec/mpegvideo_dec.c @@ -640,6 +640,7 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s, const int s_mask = (2 << lowres) - 1; const int h_edge_pos = s->h_edge_pos >> lowres; const int v_edge_pos = s->v_edge_pos >> lowres; + int hc = s->chroma_y_shift ? (h+1-bottom_field)>>1 : h; linesize = s->current_picture.f->linesize[0] << field_based; uvlinesize = s->current_picture.f->linesize[1] << field_based; @@ -702,7 +703,7 @@ 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) - h, 0)) { + (unsigned) src_y > FFMAX((v_edge_pos >> field_based) - (!!sy) - FFMAX(h, 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, @@ -747,7 +748,6 @@ static av_always_inline void mpeg_motion_lowres(MpegEncContext *s, pix_op[lowres - 1](dest_y, ptr_y, linesize, h, sx, sy); if (!CONFIG_GRAY || !(s->avctx->flags & AV_CODEC_FLAG_GRAY)) { - int hc = s->chroma_y_shift ? (h+1-bottom_field)>>1 : h; uvsx = (uvsx << 2) >> lowres; uvsy = (uvsy << 2) >> lowres; if (hc) {