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[libpng16] Compute a larger limit on IDAT because some applications write a

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deflate buffer for each row (Bug report by Andrew Church).
This commit is contained in:
Glenn Randers-Pehrson
2017-08-31 11:14:23 -05:00
parent 47aa798127
commit eb2f42aa97
3 changed files with 20 additions and 17 deletions
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26
pngrutil.c
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@@ -3144,28 +3144,28 @@ png_check_chunk_length(png_const_structrp png_ptr, const 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;
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;
if (PNG_USER_CHUNK_MALLOC_MAX < limit)
limit = PNG_USER_CHUNK_MALLOC_MAX;
# endif
}
else
if (png_ptr->chunk_name == png_IDAT)
{
png_alloc_size_t idat_limit = PNG_UINT_31_MAX;
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;
idat_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;
idat_limit = png_ptr->height * row_factor;
row_factor = row_factor > 32566? 32566 : row_factor;
idat_limit += 6 + 5*(idat_limit/row_factor+1); /* zlib+deflate overhead */
idat_limit=idat_limit < PNG_UINT_31_MAX? idat_limit : PNG_UINT_31_MAX;
limit = limit < idat_limit? idat_limit : limit;
}
if (length > limit)