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[libpng16] Moved chunk-length check into a png_check_chunk_length() private

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function (Suggested by Max Stepin).
This commit is contained in:
Glenn Randers-Pehrson
2017-08-04 14:09:27 -05:00
parent 469317d9bd
commit 2dca15686f
5 changed files with 51 additions and 66 deletions
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70
pngrutil.c
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@@ -157,7 +157,6 @@ png_read_chunk_header(png_structrp png_ptr)
{
png_byte buf[8];
png_uint_32 length;
png_alloc_size_t limit = PNG_UINT_31_MAX;
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_HDR;
@@ -183,36 +182,7 @@ png_read_chunk_header(png_structrp png_ptr)
png_check_chunk_name(png_ptr, png_ptr->chunk_name);
/* Check for too-large chunk length */
if (png_ptr->chunk_name != png_IDAT)
{
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_malloc_max > 0 &&
png_ptr->user_chunk_malloc_max < limit)
limit = png_ptr->user_chunk_malloc_max;
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
if (PNG_USER_CHUNK_MALLOC_MAX < limit)
limit = PNG_USER_CHUNK_MALLOC_MAX;
# endif
}
else
{
size_t row_factor =
(png_ptr->width * png_ptr->channels * (png_ptr->bit_depth > 8? 2: 1)
+ 1 + (png_ptr->interlaced? 6: 0));
if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
limit=PNG_UINT_31_MAX;
else
limit = png_ptr->height * row_factor;
limit += 6 + 5*(limit/32566+1); /* zlib+deflate overhead */
limit=limit < PNG_UINT_31_MAX? limit : PNG_UINT_31_MAX;
}
if (length > limit)
{
png_debug2(0," length = %lu, limit = %lu",
(unsigned long)length,(unsigned long)limit);
png_chunk_error(png_ptr, "chunk data is too large");
}
png_check_chunk_length(png_ptr, png_ptr->chunk_name, length);
#ifdef PNG_IO_STATE_SUPPORTED
png_ptr->io_state = PNG_IO_READING | PNG_IO_CHUNK_DATA;
@@ -3134,6 +3104,44 @@ png_check_chunk_name(png_structrp png_ptr, png_uint_32 chunk_name)
}
}
void /* PRIVATE */
png_check_chunk_length(png_structrp png_ptr, png_uint_32 chunk_name,
png_uint_32 length)
{
png_alloc_size_t limit = PNG_UINT_31_MAX;
if (png_ptr->chunk_name != png_IDAT)
{
# ifdef PNG_SET_USER_LIMITS_SUPPORTED
if (png_ptr->user_chunk_malloc_max > 0 &&
png_ptr->user_chunk_malloc_max < limit)
limit = png_ptr->user_chunk_malloc_max;
# elif PNG_USER_CHUNK_MALLOC_MAX > 0
if (PNG_USER_CHUNK_MALLOC_MAX < limit)
limit = PNG_USER_CHUNK_MALLOC_MAX;
# endif
}
else
{
size_t row_factor =
(png_ptr->width * png_ptr->channels * (png_ptr->bit_depth > 8? 2: 1)
+ 1 + (png_ptr->interlaced? 6: 0));
if (png_ptr->height > PNG_UINT_32_MAX/row_factor)
limit=PNG_UINT_31_MAX;
else
limit = png_ptr->height * row_factor;
limit += 6 + 5*(limit/32566+1); /* zlib+deflate overhead */
limit=limit < PNG_UINT_31_MAX? limit : PNG_UINT_31_MAX;
}
if (length > limit)
{
png_debug2(0," length = %lu, limit = %lu",
(unsigned long)length,(unsigned long)limit);
png_chunk_error(png_ptr, "chunk data is too large");
}
}
/* Combines the row recently read in with the existing pixels in the row. This
* routine takes care of alpha and transparency if requested. This routine also
* handles the two methods of progressive display of interlaced images,