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[lbipng15] Fixed the recently reported 1's complement security issue by

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replacing the value that is illegal in the PNG spec, in both signed and
  unsigned values, with 0. Illegal unsigned values (anything greater than or
  equal to  0x80000000) can still pass through, but since these are not illegal
  in ANSI-C (unlike 0x80000000 in the signed case) the checking that
  occurs later can catch them (John Bowler).

Safely convert num_bytes to a png_byte in png_set_sig_bytes() (Robert
  Seacord).
This commit is contained in:
Glenn Randers-Pehrson 2015-08-19 12:52:39 -05:00
parent a88dec67f2
commit c357fb70b5
7 changed files with 40 additions and 22 deletions
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10
ANNOUNCE
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@ -1,5 +1,5 @@
Libpng 1.5.24beta01 - August 18, 2015
Libpng 1.5.24beta01 - August 19, 2015
This is not intended to be a public release. It will be replaced
within a few weeks by a public version or by another test version.
@ -27,7 +27,7 @@ Other information:
Changes since the last public release (1.5.23):
Version 1.5.24beta01 [August 18, 2015]
Version 1.5.24beta01 [August 19, 2015]
Avoid potentially dereferencing NULL info_ptr in png_info_init_3().
Eliminated unused PNG_COST_SHIFT, PNG_WEIGHT_SHIFT, PNG_COST_FACTOR, and
PNG_WEIGHT_FACTOR macros.
@ -36,6 +36,12 @@ Version 1.5.24beta01 [August 18, 2015]
Fixed some bad links in the man page.
Safely convert num_bytes to a png_byte in png_set_sig_bytes() (Robert
Seacord).
Fixed the recently reported 1's complement security issue by replacing
the value that is illegal in the PNG spec, in both signed and unsigned
values, with 0. Illegal unsigned values (anything greater than or equal
to 0x80000000) can still pass through, but since these are not illegal
in ANSI-C (unlike 0x80000000 in the signed case) the checking that
occurs later can catch them (John Bowler).
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit

8
CHANGES
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@ -4373,7 +4373,7 @@ Version 1.5.23rc03 [July 15, 2015]
Version 1.5.23 [July 23, 2015]
No changes.
Version 1.5.24beta01 [August 18, 2015]
Version 1.5.24beta01 [August 19, 2015]
Avoid potentially dereferencing NULL info_ptr in png_info_init_3().
Eliminated unused PNG_COST_SHIFT, PNG_WEIGHT_SHIFT, PNG_COST_FACTOR, and
PNG_WEIGHT_FACTOR macros.
@ -4382,6 +4382,12 @@ Version 1.5.24beta01 [August 18, 2015]
Fixed some bad links in the man page.
Safely convert num_bytes to a png_byte in png_set_sig_bytes() (Robert
Seacord).
Fixed the recently reported 1's complement security issue by replacing
the value that is illegal in the PNG spec, in both signed and unsigned
values, with 0. Illegal unsigned values (anything greater than or equal
to 0x80000000) can still pass through, but since these are not illegal
in ANSI-C (unlike 0x80000000 in the signed case) the checking that
occurs later can catch them (John Bowler).
Send comments/corrections/commendations to png-mng-implement at lists.sf.net
(subscription required; visit

6
libpng-manual.txt
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@ -1,6 +1,6 @@
Libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.5.24beta01 - August 18, 2015
libpng version 1.5.24beta01 - August 19, 2015
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2014 Glenn Randers-Pehrson
@ -11,7 +11,7 @@ Libpng-manual.txt - A description on how to use and modify libpng
Based on:
libpng versions 0.97, January 1998, through 1.5.24beta01 - August 18, 2015
libpng versions 0.97, January 1998, through 1.5.24beta01 - August 19, 2015
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2014 Glenn Randers-Pehrson
@ -4501,7 +4501,7 @@ Other rules can be inferred by inspecting the libpng source.
XIV. Y2K Compliance in libpng
August 18, 2015
August 19, 2015
Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.

14
libpng.3
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@ -1,4 +1,4 @@
.TH LIBPNG 3 "August 18, 2015"
.TH LIBPNG 3 "August 19, 2015"
.SH NAME
libpng \- Portable Network Graphics (PNG) Reference Library 1.5.24beta01
.SH SYNOPSIS
@ -496,7 +496,7 @@ Following is a copy of the libpng-manual.txt file that accompanies libpng.
.SH LIBPNG.TXT
Libpng-manual.txt - A description on how to use and modify libpng
libpng version 1.5.24beta01 - August 18, 2015
libpng version 1.5.24beta01 - August 19, 2015
Updated and distributed by Glenn Randers-Pehrson
<glennrp at users.sourceforge.net>
Copyright (c) 1998-2014 Glenn Randers-Pehrson
@ -507,7 +507,7 @@ Libpng-manual.txt - A description on how to use and modify libpng
Based on:
libpng versions 0.97, January 1998, through 1.5.24beta01 - August 18, 2015
libpng versions 0.97, January 1998, through 1.5.24beta01 - August 19, 2015
Updated and distributed by Glenn Randers-Pehrson
Copyright (c) 1998-2014 Glenn Randers-Pehrson
@ -4997,7 +4997,7 @@ Other rules can be inferred by inspecting the libpng source.
.SH XIV. Y2K Compliance in libpng
August 18, 2015
August 19, 2015
Since the PNG Development group is an ad-hoc body, we can't make
an official declaration.
@ -5310,7 +5310,7 @@ possible without all of you.
Thanks to Frank J. T. Wojcik for helping with the documentation.
Libpng version 1.5.24beta01 - August 18, 2015:
Libpng version 1.5.24beta01 - August 19, 2015:
Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
@ -5333,7 +5333,7 @@ this sentence.
This code is released under the libpng license.
libpng versions 1.0.7, July 1, 2000, through 1.5.24beta01, August 18, 2015, are
libpng versions 1.0.7, July 1, 2000, through 1.5.24beta01, August 19, 2015, are
Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, and are
distributed according to the same disclaimer and license as libpng-1.0.6
with the following individuals added to the list of Contributing Authors:
@ -5426,7 +5426,7 @@ the additional disclaimers inserted at version 1.0.7.
Glenn Randers-Pehrson
glennrp at users.sourceforge.net
August 18, 2015
August 19, 2015
.\" end of man page

4
png.c
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@ -655,13 +655,13 @@ png_get_copyright(png_const_structp png_ptr)
#else
# ifdef __STDC__
return PNG_STRING_NEWLINE \
"libpng version 1.5.24beta01 - August 18, 2015" PNG_STRING_NEWLINE \
"libpng version 1.5.24beta01 - August 19, 2015" PNG_STRING_NEWLINE \
"Copyright (c) 1998-2015 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
"Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
"Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
PNG_STRING_NEWLINE;
# else
return "libpng version 1.5.24beta01 - August 18, 2015\
return "libpng version 1.5.24beta01 - August 19, 2015\
Copyright (c) 1998-2015 Glenn Randers-Pehrson\
Copyright (c) 1996-1997 Andreas Dilger\
Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";

12
png.h
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@ -1,7 +1,7 @@
/* png.h - header file for PNG reference library
*
* libpng version 1.5.24beta01, July 24, 2015
* libpng version 1.5.24beta01, August 19, 2015
*
* Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
@ -12,7 +12,7 @@
* Authors and maintainers:
* libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
* libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
* libpng versions 0.97, January 1998, through 1.5.24beta01, July 24, 2015: Glenn
* libpng versions 0.97, January 1998, through 1.5.24beta01, August 19, 2015: Glenn
* See also "Contributing Authors", below.
*
* Note about libpng version numbers:
@ -244,7 +244,7 @@
*
* This code is released under the libpng license.
*
* libpng versions 1.0.7, July 1, 2000, through 1.5.24beta01, July 24, 2015, are
* libpng versions 1.0.7, July 1, 2000, through 1.5.24beta01, August 19, 2015, are
* Copyright (c) 2000-2002, 2004, 2006-2015 Glenn Randers-Pehrson, and are
* distributed according to the same disclaimer and license as libpng-1.0.6
* with the following individuals added to the list of Contributing Authors:
@ -352,7 +352,7 @@
* Y2K compliance in libpng:
* =========================
*
* July 24, 2015
* August 19, 2015
*
* Since the PNG Development group is an ad-hoc body, we can't make
* an official declaration.
@ -421,7 +421,7 @@
/* Version information for png.h - this should match the version in png.c */
#define PNG_LIBPNG_VER_STRING "1.5.24beta01"
#define PNG_HEADER_VERSION_STRING \
" libpng version 1.5.24beta01 - July 24, 2015\n"
" libpng version 1.5.24beta01 - August 19, 2015\n"
#define PNG_LIBPNG_VER_SONUM 15
#define PNG_LIBPNG_VER_DLLNUM 15
@ -2652,7 +2652,7 @@ PNG_EXPORT(207, void, png_save_uint_16, (png_bytep buf, unsigned int i));
# define png_get_int_32(buf) \
((png_int_32)((*(buf) & 0x80) \
? -((png_int_32)((png_get_uint_32(buf) ^ 0xffffffffL) + 1)) \
? -((png_int_32)(((png_get_uint_32(buf)^0xffffffffU)+1U)&0x7fffffffU)) \
: (png_int_32)png_get_uint_32(buf)))
#endif

8
pngrutil.c
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@ -89,7 +89,13 @@ png_get_int_32)(png_const_bytep buf)
return uval;
uval = (uval ^ 0xffffffff) + 1; /* 2's complement: -x = ~x+1 */
return -(png_int_32)uval;
if ((uval & 0x80000000) == 0) /* no overflow */
return -(png_int_32)uval;
/* The following has to be safe; this function only gets called on PNG data
* and if we get here that data is invalid. 0 is the most safe value and
* if not then an attacker would surely just generate a PNG with 0 instead.
*/
return 0;
}
/* Grab an unsigned 16-bit integer from a buffer in big-endian format. */