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| author | Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com> | 2015-12-02 21:52:23 +0100 |
|---|---|---|
| committer | Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com> | 2015-12-06 22:40:41 +0100 |
| commit | 5adb5d9d894aa495e7bf9557b4c78350cbfc9d32 (patch) | |
| tree | ede3dcf04a9ac33336c27be7fa673ba62a8f2bf0 /libavcodec/mjpegdec.c | |
| parent | a0a39acd01ea3a98274cd10fef318a35853ff8cd (diff) | |
| download | ffmpeg-5adb5d9d894aa495e7bf9557b4c78350cbfc9d32.tar.gz | |
mjpegdec: consider chroma subsampling in size check
If the chroma components are subsampled, smaller buffers are allocated
for them. In that case the maximal block_offset for the chroma
components is not as large as for the luma component.
This fixes out of bounds writes causing segmentation faults or memory
corruption.
Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
Diffstat (limited to 'libavcodec/mjpegdec.c')
| -rw-r--r-- | libavcodec/mjpegdec.c | 11 |
1 files changed, 8 insertions, 3 deletions
diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c index 4c9c82d141..c812b86e87 100644 --- a/libavcodec/mjpegdec.c +++ b/libavcodec/mjpegdec.c @@ -1246,7 +1246,7 @@ static int mjpeg_decode_scan(MJpegDecodeContext *s, int nb_components, int Ah, int mb_bitmask_size, const AVFrame *reference) { - int i, mb_x, mb_y; + int i, mb_x, mb_y, chroma_h_shift, chroma_v_shift, chroma_width, chroma_height; uint8_t *data[MAX_COMPONENTS]; const uint8_t *reference_data[MAX_COMPONENTS]; int linesize[MAX_COMPONENTS]; @@ -1263,6 +1263,11 @@ static int mjpeg_decode_scan(MJpegDecodeContext *s, int nb_components, int Ah, s->restart_count = 0; + av_pix_fmt_get_chroma_sub_sample(s->avctx->pix_fmt, &chroma_h_shift, + &chroma_v_shift); + chroma_width = FF_CEIL_RSHIFT(s->width, chroma_h_shift); + chroma_height = FF_CEIL_RSHIFT(s->height, chroma_v_shift); + for (i = 0; i < nb_components; i++) { int c = s->comp_index[i]; data[c] = s->picture_ptr->data[c]; @@ -1299,8 +1304,8 @@ static int mjpeg_decode_scan(MJpegDecodeContext *s, int nb_components, int Ah, if (s->interlaced && s->bottom_field) block_offset += linesize[c] >> 1; - if ( 8*(h * mb_x + x) < s->width - && 8*(v * mb_y + y) < s->height) { + if ( 8*(h * mb_x + x) < ((c == 1) || (c == 2) ? chroma_width : s->width) + && 8*(v * mb_y + y) < ((c == 1) || (c == 2) ? chroma_height : s->height)) { ptr = data[c] + block_offset; } else ptr = NULL; |