[FFmpeg-cvslog] Check for out of bound reads in the Tiertex Limited SEQ decoder.
Laurent Aimar
git at videolan.org
Fri Sep 30 02:13:35 CEST 2011
ffmpeg | branch: master | Laurent Aimar <fenrir at videolan.org> | Fri Sep 30 00:05:47 2011 +0200| [5d7e3d71673d64a16b58430a0027afadb6b3a54e] | committer: Michael Niedermayer
Check for out of bound reads in the Tiertex Limited SEQ decoder.
Signed-off-by: Michael Niedermayer <michaelni at gmx.at>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5d7e3d71673d64a16b58430a0027afadb6b3a54e
---
libavcodec/tiertexseqv.c | 65 ++++++++++++++++++++++++++++++++++++----------
1 files changed, 51 insertions(+), 14 deletions(-)
diff --git a/libavcodec/tiertexseqv.c b/libavcodec/tiertexseqv.c
index 8f299be..afe84b8 100644
--- a/libavcodec/tiertexseqv.c
+++ b/libavcodec/tiertexseqv.c
@@ -35,15 +35,19 @@ typedef struct SeqVideoContext {
} SeqVideoContext;
-static const unsigned char *seq_unpack_rle_block(const unsigned char *src, unsigned char *dst, int dst_size)
+static const unsigned char *seq_unpack_rle_block(const unsigned char *src,
+ const unsigned char *src_end,
+ unsigned char *dst, int dst_size)
{
int i, len, sz;
GetBitContext gb;
int code_table[64];
- /* get the rle codes (at most 64 bytes) */
- init_get_bits(&gb, src, 64 * 8);
+ /* get the rle codes */
+ init_get_bits(&gb, src, (src_end - src) * 8);
for (i = 0, sz = 0; i < 64 && sz < dst_size; i++) {
+ if (get_bits_left(&gb) < 4)
+ return NULL;
code_table[i] = get_sbits(&gb, 4);
sz += FFABS(code_table[i]);
}
@@ -54,8 +58,12 @@ static const unsigned char *seq_unpack_rle_block(const unsigned char *src, unsig
len = code_table[i];
if (len < 0) {
len = -len;
+ if (src_end - src < 1)
+ return NULL;
memset(dst, *src++, FFMIN(len, dst_size));
} else {
+ if (src_end - src < len)
+ return NULL;
memcpy(dst, src, FFMIN(len, dst_size));
src += len;
}
@@ -65,25 +73,30 @@ static const unsigned char *seq_unpack_rle_block(const unsigned char *src, unsig
return src;
}
-static const unsigned char *seq_decode_op1(SeqVideoContext *seq, const unsigned char *src, unsigned char *dst)
+static const unsigned char *seq_decode_op1(SeqVideoContext *seq,
+ const unsigned char *src,
+ const unsigned char *src_end,
+ unsigned char *dst)
{
const unsigned char *color_table;
int b, i, len, bits;
GetBitContext gb;
unsigned char block[8 * 8];
+ if (src_end - src < 1)
+ return NULL;
len = *src++;
if (len & 0x80) {
switch (len & 3) {
case 1:
- src = seq_unpack_rle_block(src, block, sizeof(block));
+ src = seq_unpack_rle_block(src, src_end, block, sizeof(block));
for (b = 0; b < 8; b++) {
memcpy(dst, &block[b * 8], 8);
dst += seq->frame.linesize[0];
}
break;
case 2:
- src = seq_unpack_rle_block(src, block, sizeof(block));
+ src = seq_unpack_rle_block(src, src_end, block, sizeof(block));
for (i = 0; i < 8; i++) {
for (b = 0; b < 8; b++)
dst[b * seq->frame.linesize[0]] = block[i * 8 + b];
@@ -92,9 +105,13 @@ static const unsigned char *seq_decode_op1(SeqVideoContext *seq, const unsigned
break;
}
} else {
+ if (len <= 0)
+ return NULL;
+ bits = ff_log2_tab[len - 1] + 1;
+ if (src_end - src < len + 8 * bits)
+ return NULL;
color_table = src;
src += len;
- bits = ff_log2_tab[len - 1] + 1;
init_get_bits(&gb, src, bits * 8 * 8); src += bits * 8;
for (b = 0; b < 8; b++) {
for (i = 0; i < 8; i++)
@@ -106,10 +123,16 @@ static const unsigned char *seq_decode_op1(SeqVideoContext *seq, const unsigned
return src;
}
-static const unsigned char *seq_decode_op2(SeqVideoContext *seq, const unsigned char *src, unsigned char *dst)
+static const unsigned char *seq_decode_op2(SeqVideoContext *seq,
+ const unsigned char *src,
+ const unsigned char *src_end,
+ unsigned char *dst)
{
int i;
+ if (src_end - src < 8 * 8)
+ return NULL;
+
for (i = 0; i < 8; i++) {
memcpy(dst, src, 8);
src += 8;
@@ -119,11 +142,16 @@ static const unsigned char *seq_decode_op2(SeqVideoContext *seq, const unsigned
return src;
}
-static const unsigned char *seq_decode_op3(SeqVideoContext *seq, const unsigned char *src, unsigned char *dst)
+static const unsigned char *seq_decode_op3(SeqVideoContext *seq,
+ const unsigned char *src,
+ const unsigned char *src_end,
+ unsigned char *dst)
{
int pos, offset;
do {
+ if (src_end - src < 2)
+ return NULL;
pos = *src++;
offset = ((pos >> 3) & 7) * seq->frame.linesize[0] + (pos & 7);
dst[offset] = *src++;
@@ -132,8 +160,9 @@ static const unsigned char *seq_decode_op3(SeqVideoContext *seq, const unsigned
return src;
}
-static void seqvideo_decode(SeqVideoContext *seq, const unsigned char *data, int data_size)
+static int seqvideo_decode(SeqVideoContext *seq, const unsigned char *data, int data_size)
{
+ const unsigned char *data_end = data + data_size;
GetBitContext gb;
int flags, i, j, x, y, op;
unsigned char c[3];
@@ -144,6 +173,8 @@ static void seqvideo_decode(SeqVideoContext *seq, const unsigned char *data, int
if (flags & 1) {
palette = (uint32_t *)seq->frame.data[1];
+ if (data_end - data < 256 * 3)
+ return AVERROR_INVALIDDATA;
for (i = 0; i < 256; i++) {
for (j = 0; j < 3; j++, data++)
c[j] = (*data << 2) | (*data >> 4);
@@ -153,6 +184,8 @@ static void seqvideo_decode(SeqVideoContext *seq, const unsigned char *data, int
}
if (flags & 2) {
+ if (data_end - data < 128)
+ return AVERROR_INVALIDDATA;
init_get_bits(&gb, data, 128 * 8); data += 128;
for (y = 0; y < 128; y += 8)
for (x = 0; x < 256; x += 8) {
@@ -160,17 +193,20 @@ static void seqvideo_decode(SeqVideoContext *seq, const unsigned char *data, int
op = get_bits(&gb, 2);
switch (op) {
case 1:
- data = seq_decode_op1(seq, data, dst);
+ data = seq_decode_op1(seq, data, data_end, dst);
break;
case 2:
- data = seq_decode_op2(seq, data, dst);
+ data = seq_decode_op2(seq, data, data_end, dst);
break;
case 3:
- data = seq_decode_op3(seq, data, dst);
+ data = seq_decode_op3(seq, data, data_end, dst);
break;
}
+ if (!data)
+ return AVERROR_INVALIDDATA;
}
}
+ return 0;
}
static av_cold int seqvideo_decode_init(AVCodecContext *avctx)
@@ -202,7 +238,8 @@ static int seqvideo_decode_frame(AVCodecContext *avctx,
return -1;
}
- seqvideo_decode(seq, buf, buf_size);
+ if (seqvideo_decode(seq, buf, buf_size))
+ return AVERROR_INVALIDDATA;
*data_size = sizeof(AVFrame);
*(AVFrame *)data = seq->frame;
More information about the ffmpeg-cvslog
mailing list