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avcodec/mpegvideo_dec: consider interlaced lowres 4:2:0 chroma in edge emulation check better

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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 <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2023-06-08 15:47:37 +02:00
parent e736238b35
commit d7d3f1af2a
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GPG Key ID: B18E8928B3948D64
1 changed files with 2 additions and 2 deletions
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4
libavcodec/mpegvideo_dec.c
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@ -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<<s->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) {