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$NetBSD: patch-coders_png.c,v 1.3 2012/07/30 09:25:29 wiz Exp $
Tom Lane (tgl@redhat.com) found an issue in ImageMagick. Basically
CVE-2011-3026 deals with libpng memory allocation, limitations have been
added so that a bad PNG can't cause the system to allocate a lot of
memory causing a denial of service. However on further investigation of
ImageMagick Tom Lane found that PNG malloc function (Magick_png_malloc)
in turn calls AcquireMagickMemory with an improper size argument:
#ifdef PNG_USER_MEM_SUPPORTED
static png_voidp Magick_png_malloc(png_structp png_ptr,png_uint_32 size)
{
(void) png_ptr;
return((png_voidp) AcquireMagickMemory((size_t) size));
}
This is incorrect, the size argument should be declared
png_alloc_size_t according to 1.5, or png_size_t according to 1.2.
"As this function stands, it invisibly does the wrong thing for any
request over 4GB. On big-endian architectures it very possibly will
do the wrong thing even for requests less than that. So the reason why
the hard-wired 4GB limit prevents a core dump is that it masks the ABI
mismatch here."
So basically we have memory allocations problems that can probably
lead to a denial of service.
For more information please see:
https://bugzilla.redhat.com/show_bug.cgi?id=844101
https://bugzilla.redhat.com/show_bug.cgi?id=844105
--- coders/png.c.orig 2012-06-23 20:10:10.000000000 +0000
+++ coders/png.c
@@ -1360,7 +1360,7 @@ static void PNGWarningHandler(png_struct
}
#ifdef PNG_USER_MEM_SUPPORTED
-static png_voidp png_IM_malloc(png_structp png_ptr,png_uint_32 size)
+static png_voidp png_IM_malloc(png_structp png_ptr,png_alloc_size_t size)
{
(void) png_ptr;
return MagickAllocateMemory(png_voidp,(size_t) size);
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