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png: convert to bytestream2 API. 

Protects against overreads in the input buffer.

Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
CC: libav-stable@libav.org
This commit is contained in:
Ronald S. Bultje 2012-03-07 16:16:20 -08:00
parent 681e726865
commit 4c25269ced
1 changed files with 30 additions and 39 deletions
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69
libavcodec/pngdec.c
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@ -35,9 +35,7 @@
typedef struct PNGDecContext {
PNGDSPContext dsp;
const uint8_t *bytestream;
const uint8_t *bytestream_start;
const uint8_t *bytestream_end;
GetByteContext gb;
AVFrame picture1, picture2;
AVFrame *current_picture, *last_picture;
@ -362,12 +360,9 @@ static void png_handle_row(PNGDecContext *s)
static int png_decode_idat(PNGDecContext *s, int length)
{
int ret;
s->zstream.avail_in = length;
s->zstream.next_in = s->bytestream;
s->bytestream += length;
if(s->bytestream > s->bytestream_end)
return -1;
s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
s->zstream.next_in = s->gb.buffer;
bytestream2_skip(&s->gb, length);
/* decode one line if possible */
while (s->zstream.avail_in > 0) {
@ -403,15 +398,13 @@ static int decode_frame(AVCodecContext *avctx,
avctx->coded_frame= s->current_picture;
p = s->current_picture;
s->bytestream_start=
s->bytestream= buf;
s->bytestream_end= buf + buf_size;
/* check signature */
if (memcmp(s->bytestream, ff_pngsig, 8) != 0 &&
memcmp(s->bytestream, ff_mngsig, 8) != 0)
if (buf_size < 8 ||
memcmp(buf, ff_pngsig, 8) != 0 &&
memcmp(buf, ff_mngsig, 8) != 0)
return -1;
s->bytestream+= 8;
bytestream2_init(&s->gb, buf + 8, buf_size - 8);
s->y=
s->state=0;
// memset(s, 0, sizeof(PNGDecContext));
@ -423,14 +416,12 @@ static int decode_frame(AVCodecContext *avctx,
if (ret != Z_OK)
return -1;
for(;;) {
int tag32;
if (s->bytestream >= s->bytestream_end)
if (bytestream2_get_bytes_left(&s->gb) <= 0)
goto fail;
length = bytestream_get_be32(&s->bytestream);
length = bytestream2_get_be32(&s->gb);
if (length > 0x7fffffff)
goto fail;
tag32 = bytestream_get_be32(&s->bytestream);
tag = av_bswap32(tag32);
tag = bytestream2_get_le32(&s->gb);
av_dlog(avctx, "png: tag=%c%c%c%c length=%u\n",
(tag & 0xff),
((tag >> 8) & 0xff),
@ -440,18 +431,18 @@ static int decode_frame(AVCodecContext *avctx,
case MKTAG('I', 'H', 'D', 'R'):
if (length != 13)
goto fail;
s->width = bytestream_get_be32(&s->bytestream);
s->height = bytestream_get_be32(&s->bytestream);
s->width = bytestream2_get_be32(&s->gb);
s->height = bytestream2_get_be32(&s->gb);
if(av_image_check_size(s->width, s->height, 0, avctx)){
s->width= s->height= 0;
goto fail;
}
s->bit_depth = *s->bytestream++;
s->color_type = *s->bytestream++;
s->compression_type = *s->bytestream++;
s->filter_type = *s->bytestream++;
s->interlace_type = *s->bytestream++;
s->bytestream += 4; /* crc */
s->bit_depth = bytestream2_get_byte(&s->gb);
s->color_type = bytestream2_get_byte(&s->gb);
s->compression_type = bytestream2_get_byte(&s->gb);
s->filter_type = bytestream2_get_byte(&s->gb);
s->interlace_type = bytestream2_get_byte(&s->gb);
bytestream2_skip(&s->gb, 4); /* crc */
s->state |= PNG_IHDR;
av_dlog(avctx, "width=%d height=%d depth=%d color_type=%d compression_type=%d filter_type=%d interlace_type=%d\n",
s->width, s->height, s->bit_depth, s->color_type,
@ -547,7 +538,7 @@ static int decode_frame(AVCodecContext *avctx,
s->state |= PNG_IDAT;
if (png_decode_idat(s, length) < 0)
goto fail;
s->bytestream += 4; /* crc */
bytestream2_skip(&s->gb, 4); /* crc */
break;
case MKTAG('P', 'L', 'T', 'E'):
{
@ -558,16 +549,16 @@ static int decode_frame(AVCodecContext *avctx,
/* read the palette */
n = length / 3;
for(i=0;i<n;i++) {
r = *s->bytestream++;
g = *s->bytestream++;
b = *s->bytestream++;
r = bytestream2_get_byte(&s->gb);
g = bytestream2_get_byte(&s->gb);
b = bytestream2_get_byte(&s->gb);
s->palette[i] = (0xff << 24) | (r << 16) | (g << 8) | b;
}
for(;i<256;i++) {
s->palette[i] = (0xff << 24);
}
s->state |= PNG_PLTE;
s->bytestream += 4; /* crc */
bytestream2_skip(&s->gb, 4); /* crc */
}
break;
case MKTAG('t', 'R', 'N', 'S'):
@ -580,21 +571,21 @@ static int decode_frame(AVCodecContext *avctx,
!(s->state & PNG_PLTE))
goto skip_tag;
for(i=0;i<length;i++) {
v = *s->bytestream++;
v = bytestream2_get_byte(&s->gb);
s->palette[i] = (s->palette[i] & 0x00ffffff) | (v << 24);
}
s->bytestream += 4; /* crc */
bytestream2_skip(&s->gb, 4); /* crc */
}
break;
case MKTAG('I', 'E', 'N', 'D'):
if (!(s->state & PNG_ALLIMAGE))
goto fail;
s->bytestream += 4; /* crc */
bytestream2_skip(&s->gb, 4); /* crc */
goto exit_loop;
default:
/* skip tag */
skip_tag:
s->bytestream += length + 4;
bytestream2_skip(&s->gb, length + 4);
break;
}
}
@ -619,7 +610,7 @@ static int decode_frame(AVCodecContext *avctx,
*picture= *s->current_picture;
*data_size = sizeof(AVFrame);
ret = s->bytestream - s->bytestream_start;
ret = bytestream2_tell(&s->gb);
the_end:
inflateEnd(&s->zstream);
av_free(crow_buf_base);