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authorAndreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>2015-12-02 21:52:23 +0100
committerMichael Niedermayer <michael@niedermayer.cc>2015-12-07 01:34:16 +0100
commit073fcfe35800d0ad400dd1668727e3741e2a6a34 (patch)
treeb42e669d04ffe9fe9bceef8fef871ab42ad64ac7
parent9f0e36b1011619121fd646b58ea778fb2553b320 (diff)
downloadffmpeg-073fcfe35800d0ad400dd1668727e3741e2a6a34.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> (cherry picked from commit 5adb5d9d894aa495e7bf9557b4c78350cbfc9d32) Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
-rw-r--r--libavcodec/mjpegdec.c11
1 files changed, 8 insertions, 3 deletions
diff --git a/libavcodec/mjpegdec.c b/libavcodec/mjpegdec.c
index 59cbd25a6e..c98476674a 100644
--- a/libavcodec/mjpegdec.c
+++ b/libavcodec/mjpegdec.c
@@ -1197,7 +1197,7 @@ 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];
@@ -1214,6 +1214,11 @@ 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];
@@ -1250,8 +1255,8 @@ 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;