[FFmpeg-cvslog] lagarith: fix buffer overreads.
Ronald S. Bultje
git at videolan.org
Thu May 3 00:26:21 CEST 2012
ffmpeg | branch: release/0.10 | Ronald S. Bultje <rsbultje at gmail.com> | Tue Mar 27 12:26:46 2012 -0700| [d6372e80fe5b9fc243632926fe023bc47ae5cca1] | committer: Reinhard Tartler
lagarith: fix buffer overreads.
Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable at libav.org
(cherry picked from commit 0a82f5275f719e6e369a807720a2c3603aa0ddd9)
Signed-off-by: Reinhard Tartler <siretart at tauware.de>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d6372e80fe5b9fc243632926fe023bc47ae5cca1
---
libavcodec/lagarith.c | 74 +++++++++++++++++++++++++++++++--------------
libavcodec/lagarithrac.c | 5 ++-
2 files changed, 54 insertions(+), 25 deletions(-)
diff --git a/libavcodec/lagarith.c b/libavcodec/lagarith.c
index 757873e..6828ba8 100644
--- a/libavcodec/lagarith.c
+++ b/libavcodec/lagarith.c
@@ -247,24 +247,26 @@ static void lag_pred_line(LagarithContext *l, uint8_t *buf,
{
int L, TL;
- /* Left pixel is actually prev_row[width] */
- L = buf[width - stride - 1];
if (!line) {
/* Left prediction only for first line */
L = l->dsp.add_hfyu_left_prediction(buf + 1, buf + 1,
width - 1, buf[0]);
- return;
- } else if (line == 1) {
- /* Second line, left predict first pixel, the rest of the line is median predicted
- * NOTE: In the case of RGB this pixel is top predicted */
- TL = l->avctx->pix_fmt == PIX_FMT_YUV420P ? buf[-stride] : L;
} else {
- /* Top left is 2 rows back, last pixel */
- TL = buf[width - (2 * stride) - 1];
- }
+ /* Left pixel is actually prev_row[width] */
+ L = buf[width - stride - 1];
+
+ if (line == 1) {
+ /* Second line, left predict first pixel, the rest of the line is median predicted
+ * NOTE: In the case of RGB this pixel is top predicted */
+ TL = l->avctx->pix_fmt == PIX_FMT_YUV420P ? buf[-stride] : L;
+ } else {
+ /* Top left is 2 rows back, last pixel */
+ TL = buf[width - (2 * stride) - 1];
+ }
- add_lag_median_prediction(buf, buf - stride, buf,
- width, &L, &TL);
+ add_lag_median_prediction(buf, buf - stride, buf,
+ width, &L, &TL);
+ }
}
static int lag_decode_line(LagarithContext *l, lag_rac *rac,
@@ -310,13 +312,13 @@ handle_zeros:
}
static int lag_decode_zero_run_line(LagarithContext *l, uint8_t *dst,
- const uint8_t *src, int width,
- int esc_count)
+ const uint8_t *src, const uint8_t *src_end,
+ int width, int esc_count)
{
int i = 0;
int count;
uint8_t zero_run = 0;
- const uint8_t *start = src;
+ const uint8_t *src_start = src;
uint8_t mask1 = -(esc_count < 2);
uint8_t mask2 = -(esc_count < 3);
uint8_t *end = dst + (width - 2);
@@ -333,6 +335,8 @@ output_zeros:
i = 0;
while (!zero_run && dst + i < end) {
i++;
+ if (src + i >= src_end)
+ return AVERROR_INVALIDDATA;
zero_run =
!(src[i] | (src[i + 1] & mask1) | (src[i + 2] & mask2));
}
@@ -348,9 +352,10 @@ output_zeros:
} else {
memcpy(dst, src, i);
src += i;
+ dst += i;
}
}
- return start - src;
+ return src_start - src;
}
@@ -366,6 +371,7 @@ static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
int esc_count = src[0];
GetBitContext gb;
lag_rac rac;
+ const uint8_t *src_end = src + src_size;
rac.avctx = l->avctx;
l->zeros = 0;
@@ -396,10 +402,16 @@ static int lag_decode_arith_plane(LagarithContext *l, uint8_t *dst,
esc_count -= 4;
if (esc_count > 0) {
/* Zero run coding only, no range coding. */
- for (i = 0; i < height; i++)
- src += lag_decode_zero_run_line(l, dst + (i * stride), src,
- width, esc_count);
+ for (i = 0; i < height; i++) {
+ int res = lag_decode_zero_run_line(l, dst + (i * stride), src,
+ src_end, width, esc_count);
+ if (res < 0)
+ return res;
+ src += res;
+ }
} else {
+ if (src_size < width * height)
+ return AVERROR_INVALIDDATA; // buffer not big enough
/* Plane is stored uncompressed */
for (i = 0; i < height; i++) {
memcpy(dst + (i * stride), src, width);
@@ -506,11 +518,19 @@ static int lag_decode_frame(AVCodecContext *avctx,
}
for (i = 0; i < planes; i++)
srcs[i] = l->rgb_planes + (i + 1) * l->rgb_stride * avctx->height - l->rgb_stride;
+ if (offset_ry >= buf_size ||
+ offset_gu >= buf_size ||
+ offset_bv >= buf_size ||
+ (planes == 4 && offs[3] >= buf_size)) {
+ av_log(avctx, AV_LOG_ERROR,
+ "Invalid frame offsets\n");
+ return AVERROR_INVALIDDATA;
+ }
for (i = 0; i < planes; i++)
lag_decode_arith_plane(l, srcs[i],
avctx->width, avctx->height,
-l->rgb_stride, buf + offs[i],
- buf_size);
+ buf_size - offs[i]);
dst = p->data[0];
for (i = 0; i < planes; i++)
srcs[i] = l->rgb_planes + i * l->rgb_stride * avctx->height;
@@ -544,15 +564,23 @@ static int lag_decode_frame(AVCodecContext *avctx,
return -1;
}
+ if (offset_ry >= buf_size ||
+ offset_gu >= buf_size ||
+ offset_bv >= buf_size) {
+ av_log(avctx, AV_LOG_ERROR,
+ "Invalid frame offsets\n");
+ return AVERROR_INVALIDDATA;
+ }
+
lag_decode_arith_plane(l, p->data[0], avctx->width, avctx->height,
p->linesize[0], buf + offset_ry,
- buf_size);
+ buf_size - offset_ry);
lag_decode_arith_plane(l, p->data[2], avctx->width / 2,
avctx->height / 2, p->linesize[2],
- buf + offset_gu, buf_size);
+ buf + offset_gu, buf_size - offset_gu);
lag_decode_arith_plane(l, p->data[1], avctx->width / 2,
avctx->height / 2, p->linesize[1],
- buf + offset_bv, buf_size);
+ buf + offset_bv, buf_size - offset_bv);
break;
default:
av_log(avctx, AV_LOG_ERROR,
diff --git a/libavcodec/lagarithrac.c b/libavcodec/lagarithrac.c
index ab7a600..f85e012 100644
--- a/libavcodec/lagarithrac.c
+++ b/libavcodec/lagarithrac.c
@@ -32,15 +32,16 @@
void lag_rac_init(lag_rac *l, GetBitContext *gb, int length)
{
- int i, j;
+ int i, j, left;
/* According to reference decoder "1st byte is garbage",
* however, it gets skipped by the call to align_get_bits()
*/
align_get_bits(gb);
+ left = get_bits_left(gb) >> 3;
l->bytestream_start =
l->bytestream = gb->buffer + get_bits_count(gb) / 8;
- l->bytestream_end = l->bytestream_start + length;
+ l->bytestream_end = l->bytestream_start + FFMIN(length, left);
l->range = 0x80;
l->low = *l->bytestream >> 1;
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