ffmpeg | branch: release/2.7 | Andreas Cadhalpun <andreas.cadhal...@googlemail.com> | Wed Dec 2 21:52:23 2015 +0100| [9a8d2f51cf0548aa3724e2a46e58416b333c755f] | committer: Michael Niedermayer
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 <mich...@niedermayer.cc> Signed-off-by: Andreas Cadhalpun <andreas.cadhal...@googlemail.com> (cherry picked from commit 5adb5d9d894aa495e7bf9557b4c78350cbfc9d32) Signed-off-by: Michael Niedermayer <mich...@niedermayer.cc> > http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=9a8d2f51cf0548aa3724e2a46e58416b333c755f --- libavcodec/mjpegdec.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c index 30fc99a..48f5ca4 100644 --- a/libavcodec/mjpegdec.c +++ b/libavcodec/mjpegdec.c @@ -1241,7 +1241,7 @@ 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]; @@ -1258,6 +1258,11 @@ 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]; @@ -1294,8 +1299,8 @@ 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; _______________________________________________ ffmpeg-cvslog mailing list ffmpeg-cvslog@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-cvslog
