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[libpng12] Prevent writing over-length PLTE chunk (Cosmin Truta) and

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silently truncate over-length PLTE chunk while reading.
This commit is contained in:
Glenn Randers-Pehrson 2015-10-31 08:39:01 -05:00
parent 856a76b285
commit 475bab6170
4 changed files with 29 additions and 10 deletions
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15
pngrutil.c
View File

@ -1,7 +1,7 @@
/* pngrutil.c - utilities to read a PNG file /* pngrutil.c - utilities to read a PNG file
* *
* Last changed in libpng 1.2.53 [February 26, 2015] * Last changed in libpng 1.2.54 [October 31, 2015]
* Copyright (c) 1998-2015 Glenn Randers-Pehrson * Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@ -506,7 +506,7 @@ void /* PRIVATE */
png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length) png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
{ {
png_color palette[PNG_MAX_PALETTE_LENGTH]; png_color palette[PNG_MAX_PALETTE_LENGTH];
int num, i; int max_palette_length, num, i;
#ifdef PNG_POINTER_INDEXING_SUPPORTED #ifdef PNG_POINTER_INDEXING_SUPPORTED
png_colorp pal_ptr; png_colorp pal_ptr;
#endif #endif
@ -558,8 +558,19 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
} }
} }
max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
(1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
/* The cast is safe because 'length' is less than 3*PNG_MAX_PALETTE_LENGTH */
num = (int)length / 3; num = (int)length / 3;
/* If the palette has 256 or fewer entries but is too large for the bit depth,
* we don't issue an error, to preserve the behavior of previous libpng versions.
* We silently truncate the unused extra palette entries here.
*/
if (num > max_palette_length)
num = max_palette_length;
#ifdef PNG_POINTER_INDEXING_SUPPORTED #ifdef PNG_POINTER_INDEXING_SUPPORTED
for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++) for (i = 0, pal_ptr = palette; i < num; i++, pal_ptr++)
{ {

13
pngset.c
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@ -1,7 +1,7 @@
/* pngset.c - storage of image information into info struct /* pngset.c - storage of image information into info struct
* *
* Last changed in libpng 1.2.53 [February 26, 2015] * Last changed in libpng 1.2.54 [October 31, 2015]
* Copyright (c) 1998-2015 Glenn Randers-Pehrson * Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@ -449,12 +449,17 @@ png_set_PLTE(png_structp png_ptr, png_infop info_ptr,
png_colorp palette, int num_palette) png_colorp palette, int num_palette)
{ {
png_uint_32 max_palette_length;
png_debug1(1, "in %s storage function", "PLTE"); png_debug1(1, "in %s storage function", "PLTE");
if (png_ptr == NULL || info_ptr == NULL) if (png_ptr == NULL || info_ptr == NULL)
return; return;
if (num_palette < 0 || num_palette > PNG_MAX_PALETTE_LENGTH) max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
(1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
if (num_palette < 0 || num_palette > (int) max_palette_length)
{ {
if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
png_error(png_ptr, "Invalid palette length"); png_error(png_ptr, "Invalid palette length");
@ -474,8 +479,8 @@ png_set_PLTE(png_structp png_ptr, png_infop info_ptr,
#endif #endif
/* Changed in libpng-1.2.1 to allocate PNG_MAX_PALETTE_LENGTH instead /* Changed in libpng-1.2.1 to allocate PNG_MAX_PALETTE_LENGTH instead
* of num_palette entries, in case of an invalid PNG file that has * of num_palette entries, in case of an invalid PNG file or incorrect
* too-large sample values. * call to png_set_PLTE() with too-large sample values.
*/ */
png_ptr->palette = (png_colorp)png_calloc(png_ptr, png_ptr->palette = (png_colorp)png_calloc(png_ptr,
PNG_MAX_PALETTE_LENGTH * png_sizeof(png_color)); PNG_MAX_PALETTE_LENGTH * png_sizeof(png_color));

2
pngwrite.c
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@ -1,7 +1,7 @@
/* pngwrite.c - general routines to write a PNG file /* pngwrite.c - general routines to write a PNG file
* *
* Last changed in libpng 1.2.53 [February 26, 2015] * Last changed in libpng 1.2.54 [October 31, 2015]
* Copyright (c) 1998-2015 Glenn Randers-Pehrson * Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)

9
pngwutil.c
View File

@ -1,7 +1,7 @@
/* pngwutil.c - utilities to write a PNG file /* pngwutil.c - utilities to write a PNG file
* *
* Last changed in libpng 1.2.53 [February 26, 2015] * Last changed in libpng 1.2.54 [October 31, 2015]
* Copyright (c) 1998-2015 Glenn Randers-Pehrson * Copyright (c) 1998-2015 Glenn Randers-Pehrson
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger) * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.) * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@ -575,17 +575,20 @@ png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
#ifdef PNG_USE_LOCAL_ARRAYS #ifdef PNG_USE_LOCAL_ARRAYS
PNG_PLTE; PNG_PLTE;
#endif #endif
png_uint_32 i; png_uint_32 max_palette_length, i;
png_colorp pal_ptr; png_colorp pal_ptr;
png_byte buf[3]; png_byte buf[3];
png_debug(1, "in png_write_PLTE"); png_debug(1, "in png_write_PLTE");
max_palette_length = (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) ?
(1 << png_ptr->bit_depth) : PNG_MAX_PALETTE_LENGTH;
if (( if ((
#ifdef PNG_MNG_FEATURES_SUPPORTED #ifdef PNG_MNG_FEATURES_SUPPORTED
!(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) && !(png_ptr->mng_features_permitted & PNG_FLAG_MNG_EMPTY_PLTE) &&
#endif #endif
num_pal == 0) || num_pal > 256) num_pal == 0) || num_pal > max_palette_length)
{ {
if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE) if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
{ {