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[libpng15] Revise pngrutil.c with a more generous size limit for IDAT chunks.

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This commit is contained in:
Glenn Randers-Pehrson 2017-09-03 09:06:48 -05:00
parent 99a7952dab
commit 9a414e2c8f
2 changed files with 20 additions and 15 deletions
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7
CHANGES
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@ -4540,6 +4540,7 @@ version 1.5.29beta01 [April 1, 2017]
Update Sourceforge URLs in documentation (https instead of http).
version 1.5.29beta02 [August 9, 2017]
Added png_check_chunk_length() function (Fixes CVE-2017-12652).
Moved chunk-name and chunk-length checks into PNG_EXTERN private
png_check_chunk_name() and png_check_chunk_length() functions
(Suggested by Max Stepin).
@ -4550,7 +4551,7 @@ version 1.5.29beta02 [August 9, 2017]
version 1.5.29rc01 [August 19, 2017]
No changes.
version 1.5.29 [August 28, 2017]
version 1.5.29 [September 3, 2017]
No changes.
Version 1.5.30beta01 [August 28, 2017]
@ -4559,6 +4560,10 @@ Version 1.5.30beta01 [August 28, 2017]
Fixed off-by-one error in png_do_check_palette_indexes() (Bug report
by Mick P., Source Forge Issue #269).
Version 1.5.30beta02 [September 3, 2017]
Compute a larger limit on IDAT because some applications write a deflate
buffer for each row (Bug report by Andrew Church).
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28
pngrutil.c
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@ -1,7 +1,7 @@
/* pngrutil.c - utilities to read a PNG file
*
* Last changed in libpng 1.5.29 [August 24, 2017]
* Last changed in libpng 1.5.30 [(PENDING RELEASE)]
* Copyright (c) 1998-2002,2004,2006-2015,2017 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@ -2826,28 +2826,28 @@ png_check_chunk_length(png_structp png_ptr, png_uint_32 length)
{
png_uint_32 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)