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ulti: Fix invalid reads 

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Gaurav Narula 2011-12-13 23:11:37 +05:30 committed by Martin Storsjö
parent 4badb386ce
commit a99273ebf3
1 changed files with 24 additions and 2 deletions
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26
libavcodec/ulti.c
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@ -40,6 +40,14 @@ typedef struct UltimotionDecodeContext {
const uint8_t *ulti_codebook;
} UltimotionDecodeContext;
#define CHECK_OVERREAD_SIZE(size) \
do { \
if (buf_end - buf < (size)) { \
av_log(avctx, AV_LOG_ERROR, "Insufficient data\n"); \
return AVERROR_INVALIDDATA; \
} \
} while(0)
static av_cold int ulti_decode_init(AVCodecContext *avctx)
{
UltimotionDecodeContext *s = avctx->priv_data;
@ -223,6 +231,7 @@ static int ulti_decode_frame(AVCodecContext *avctx,
int i;
int skip;
int tmp;
const uint8_t *buf_end = buf + buf_size;
s->frame.reference = 1;
s->frame.buffer_hints = FF_BUFFER_HINTS_VALID | FF_BUFFER_HINTS_PRESERVE | FF_BUFFER_HINTS_REUSABLE;
@ -236,10 +245,12 @@ static int ulti_decode_frame(AVCodecContext *avctx,
if(blocks >= s->blocks || y >= s->height)
break;//all blocks decoded
CHECK_OVERREAD_SIZE(1);
idx = *buf++;
if((idx & 0xF8) == 0x70) {
switch(idx) {
case 0x70: //change modifier
CHECK_OVERREAD_SIZE(1);
modifier = *buf++;
if(modifier>1)
av_log(avctx, AV_LOG_INFO, "warning: modifier must be 0 or 1, got %i\n", modifier);
@ -254,6 +265,7 @@ static int ulti_decode_frame(AVCodecContext *avctx,
done = 1;
break;
case 0x74: //skip some blocks
CHECK_OVERREAD_SIZE(1);
skip = *buf++;
if ((blocks + skip) >= s->blocks)
break;
@ -280,19 +292,24 @@ static int ulti_decode_frame(AVCodecContext *avctx,
chroma = 0;
} else {
cf = 0;
if (idx)
if (idx) {
CHECK_OVERREAD_SIZE(1);
chroma = *buf++;
}
}
for (i = 0; i < 4; i++) { // for every subblock
code = (idx >> (6 - i*2)) & 3; //extract 2 bits
if(!code) //skip subblock
continue;
if(cf)
if(cf) {
CHECK_OVERREAD_SIZE(1);
chroma = *buf++;
}
tx = x + block_coords[i * 2];
ty = y + block_coords[(i * 2) + 1];
switch(code) {
case 1:
CHECK_OVERREAD_SIZE(1);
tmp = *buf++;
angle = angle_by_index[(tmp >> 6) & 0x3];
@ -313,6 +330,7 @@ static int ulti_decode_frame(AVCodecContext *avctx,
case 2:
if (modifier) { // unpack four luma samples
CHECK_OVERREAD_SIZE(3);
tmp = bytestream_get_be24(&buf);
Y[0] = (tmp >> 18) & 0x3F;
@ -321,6 +339,7 @@ static int ulti_decode_frame(AVCodecContext *avctx,
Y[3] = tmp & 0x3F;
angle = 16;
} else { // retrieve luma samples from codebook
CHECK_OVERREAD_SIZE(2);
tmp = bytestream_get_be16(&buf);
angle = (tmp >> 12) & 0xF;
@ -337,6 +356,8 @@ static int ulti_decode_frame(AVCodecContext *avctx,
if (modifier) { // all 16 luma samples
uint8_t Luma[16];
CHECK_OVERREAD_SIZE(12);
tmp = bytestream_get_be24(&buf);
Luma[0] = (tmp >> 18) & 0x3F;
Luma[1] = (tmp >> 12) & 0x3F;
@ -363,6 +384,7 @@ static int ulti_decode_frame(AVCodecContext *avctx,
ulti_convert_yuv(&s->frame, tx, ty, Luma, chroma);
} else {
CHECK_OVERREAD_SIZE(4);
tmp = *buf++;
if(tmp & 0x80) {
angle = (tmp >> 4) & 0x7;