[FFmpeg-cvslog] vmd: fix segfaults on corruped streams
Laurent Aimar
git at videolan.org
Thu Dec 8 01:17:39 CET 2011
ffmpeg | branch: release/0.8 | Laurent Aimar <fenrir at videolan.org> | Sun Sep 11 19:17:45 2011 +0200| [494cfacdb9ba3f0549e37f76b3a2f86a7aeeac3c] | committer: Reinhard Tartler
vmd: fix segfaults on corruped streams
Signed-off-by: Janne Grunau <janne-libav at jannau.net>
Signed-off-by: Reinhard Tartler <siretart at tauware.de>
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=494cfacdb9ba3f0549e37f76b3a2f86a7aeeac3c
---
libavcodec/vmdav.c | 104 ++++++++++++++++++++++++++++++++++++++++------------
1 files changed, 80 insertions(+), 24 deletions(-)
diff --git a/libavcodec/vmdav.c b/libavcodec/vmdav.c
index d258252..500adcb 100644
--- a/libavcodec/vmdav.c
+++ b/libavcodec/vmdav.c
@@ -72,9 +72,11 @@ typedef struct VmdVideoContext {
#define QUEUE_SIZE 0x1000
#define QUEUE_MASK 0x0FFF
-static void lz_unpack(const unsigned char *src, unsigned char *dest, int dest_len)
+static void lz_unpack(const unsigned char *src, int src_len,
+ unsigned char *dest, int dest_len)
{
const unsigned char *s;
+ unsigned int s_len;
unsigned char *d;
unsigned char *d_end;
unsigned char queue[QUEUE_SIZE];
@@ -87,13 +89,16 @@ static void lz_unpack(const unsigned char *src, unsigned char *dest, int dest_le
unsigned int i, j;
s = src;
+ s_len = src_len;
d = dest;
d_end = d + dest_len;
dataleft = AV_RL32(s);
- s += 4;
+ s += 4; s_len -= 4;
memset(queue, 0x20, QUEUE_SIZE);
+ if (s_len < 4)
+ return;
if (AV_RL32(s) == 0x56781234) {
- s += 4;
+ s += 4; s_len -= 4;
qpos = 0x111;
speclen = 0xF + 3;
} else {
@@ -101,32 +106,41 @@ static void lz_unpack(const unsigned char *src, unsigned char *dest, int dest_le
speclen = 100; /* no speclen */
}
- while (dataleft > 0) {
- tag = *s++;
+ while (dataleft > 0 && s_len > 0) {
+ tag = *s++; s_len--;
if ((tag == 0xFF) && (dataleft > 8)) {
- if (d + 8 > d_end)
+ if (d + 8 > d_end || s_len < 8)
return;
for (i = 0; i < 8; i++) {
queue[qpos++] = *d++ = *s++;
qpos &= QUEUE_MASK;
}
+ s_len -= 8;
dataleft -= 8;
} else {
for (i = 0; i < 8; i++) {
if (dataleft == 0)
break;
if (tag & 0x01) {
- if (d + 1 > d_end)
+ if (d + 1 > d_end || s_len < 1)
return;
queue[qpos++] = *d++ = *s++;
qpos &= QUEUE_MASK;
dataleft--;
+ s_len--;
} else {
+ if (s_len < 2)
+ return;
chainofs = *s++;
chainofs |= ((*s & 0xF0) << 4);
chainlen = (*s++ & 0x0F) + 3;
- if (chainlen == speclen)
+ s_len -= 2;
+ if (chainlen == speclen) {
+ if (s_len < 1)
+ return;
chainlen = *s++ + 0xF + 3;
+ s_len--;
+ }
if (d + chainlen > d_end)
return;
for (j = 0; j < chainlen; j++) {
@@ -143,7 +157,7 @@ static void lz_unpack(const unsigned char *src, unsigned char *dest, int dest_le
}
static int rle_unpack(const unsigned char *src, unsigned char *dest,
- int src_len, int dest_len)
+ int src_count, int src_size, int dest_len)
{
const unsigned char *ps;
unsigned char *pd;
@@ -152,31 +166,40 @@ static int rle_unpack(const unsigned char *src, unsigned char *dest,
ps = src;
pd = dest;
- if (src_len & 1)
+ if (src_count & 1) {
+ if (src_size < 1)
+ return 0;
*pd++ = *ps++;
+ src_size--;
+ }
- src_len >>= 1;
+ src_count >>= 1;
i = 0;
do {
+ if (src_size < 1)
+ break;
l = *ps++;
+ src_size--;
if (l & 0x80) {
l = (l & 0x7F) * 2;
- if (pd + l > dest_end)
+ if (pd + l > dest_end || src_size < l)
return ps - src;
memcpy(pd, ps, l);
ps += l;
+ src_size -= l;
pd += l;
} else {
- if (pd + i > dest_end)
+ if (pd + i > dest_end || src_size < 2)
return ps - src;
for (i = 0; i < l; i++) {
*pd++ = ps[0];
*pd++ = ps[1];
}
ps += 2;
+ src_size -= 2;
}
i += l;
- } while (i < src_len);
+ } while (i < src_count);
return ps - src;
}
@@ -191,6 +214,7 @@ static void vmd_decode(VmdVideoContext *s)
const unsigned char *p = s->buf + 16;
const unsigned char *pb;
+ unsigned int pb_size;
unsigned char meth;
unsigned char *dp; /* pointer to current frame */
unsigned char *pp; /* pointer to previous frame */
@@ -204,6 +228,16 @@ static void vmd_decode(VmdVideoContext *s)
frame_y = AV_RL16(&s->buf[8]);
frame_width = AV_RL16(&s->buf[10]) - frame_x + 1;
frame_height = AV_RL16(&s->buf[12]) - frame_y + 1;
+ if (frame_x < 0 || frame_width < 0 ||
+ frame_x >= s->avctx->width ||
+ frame_width > s->avctx->width ||
+ frame_x + frame_width > s->avctx->width)
+ return;
+ if (frame_y < 0 || frame_height < 0 ||
+ frame_y >= s->avctx->height ||
+ frame_height > s->avctx->height ||
+ frame_y + frame_height > s->avctx->height)
+ return;
if ((frame_width == s->avctx->width && frame_height == s->avctx->height) &&
(frame_x || frame_y)) {
@@ -216,8 +250,9 @@ static void vmd_decode(VmdVideoContext *s)
/* if only a certain region will be updated, copy the entire previous
* frame before the decode */
- if (frame_x || frame_y || (frame_width != s->avctx->width) ||
- (frame_height != s->avctx->height)) {
+ if (s->prev_frame.data[0] &&
+ (frame_x || frame_y || (frame_width != s->avctx->width) ||
+ (frame_height != s->avctx->height))) {
memcpy(s->frame.data[0], s->prev_frame.data[0],
s->avctx->height * s->frame.linesize[0]);
@@ -235,14 +270,19 @@ static void vmd_decode(VmdVideoContext *s)
}
s->size -= (256 * 3 + 2);
}
- if (s->size >= 0) {
+ if (s->size > 0) {
/* originally UnpackFrame in VAG's code */
pb = p;
- meth = *pb++;
+ pb_size = s->buf + s->size - pb;
+ if (pb_size < 1)
+ return;
+ meth = *pb++; pb_size--;
if (meth & 0x80) {
- lz_unpack(pb, s->unpack_buffer, s->unpack_buffer_size);
+ lz_unpack(pb, pb_size,
+ s->unpack_buffer, s->unpack_buffer_size);
meth &= 0x7F;
pb = s->unpack_buffer;
+ pb_size = s->unpack_buffer_size;
}
dp = &s->frame.data[0][frame_y * s->frame.linesize[0] + frame_x];
@@ -252,17 +292,21 @@ static void vmd_decode(VmdVideoContext *s)
for (i = 0; i < frame_height; i++) {
ofs = 0;
do {
+ if (pb_size < 1)
+ return;
len = *pb++;
+ pb_size--;
if (len & 0x80) {
len = (len & 0x7F) + 1;
- if (ofs + len > frame_width)
+ if (ofs + len > frame_width || pb_size < len)
return;
memcpy(&dp[ofs], pb, len);
pb += len;
+ pb_size -= len;
ofs += len;
} else {
/* interframe pixel copy */
- if (ofs + len + 1 > frame_width)
+ if (ofs + len + 1 > frame_width || !s->prev_frame.data[0])
return;
memcpy(&dp[ofs], &pp[ofs], len + 1);
ofs += len + 1;
@@ -280,8 +324,11 @@ static void vmd_decode(VmdVideoContext *s)
case 2:
for (i = 0; i < frame_height; i++) {
+ if (pb_size < frame_width)
+ return;
memcpy(dp, pb, frame_width);
pb += frame_width;
+ pb_size -= frame_width;
dp += s->frame.linesize[0];
pp += s->prev_frame.linesize[0];
}
@@ -291,18 +338,27 @@ static void vmd_decode(VmdVideoContext *s)
for (i = 0; i < frame_height; i++) {
ofs = 0;
do {
+ if (pb_size < 1)
+ return;
len = *pb++;
+ pb_size--;
if (len & 0x80) {
len = (len & 0x7F) + 1;
+ if (pb_size < 1)
+ return;
if (*pb++ == 0xFF)
- len = rle_unpack(pb, &dp[ofs], len, frame_width - ofs);
- else
+ len = rle_unpack(pb, &dp[ofs], len, pb_size, frame_width - ofs);
+ else {
+ if (pb_size < len)
+ return;
memcpy(&dp[ofs], pb, len);
+ }
pb += len;
+ pb_size -= 1 + len;
ofs += len;
} else {
/* interframe pixel copy */
- if (ofs + len + 1 > frame_width)
+ if (ofs + len + 1 > frame_width || !s->prev_frame.data[0])
return;
memcpy(&dp[ofs], &pp[ofs], len + 1);
ofs += len + 1;
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