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Date: Tue, 5 Jun 2012 01:54:17 -0400
From: Xi Wang <xi.wang@...il.com>
To: oss-security@...ts.openwall.com
Subject: memory allocator upstream patches

Hi,

I would like to share some upstream patches of two specific types
of memory allocator vulnerabilities.

* malloc(n) size overflow.

Consider the following code pattern.

	n = read_from_input();
	p = malloc(n);
	if (p)
		memcpy(p, input_buffer, n);

Some malloc() implementations internally perform alignment/padding
for a large n, and the allocation size wraps around to a small
integer.  That means they would allocate a smaller buffer than
expected, leading to buffer overflow.

* calloc(n, size) size overflow.

Some calloc() implementations don't check for n * size multiplication
overflow, and would allocate a smaller buffer than expected,
leading to buffer overflow.

The two types of vulnerabilities can be easily reproduced using
malloc(-1) and calloc(BIG-VALUE, BIG-VALUE).  If the return values
are non-null, the implementations are likely to be problematic.

See a more complete list at:

http://kqueue.org/blog/2012/03/05/memory-allocator-security-revisited/

Below are some recent upstream fixes.


Boehm-Demers-Weiser GC (libgc)
==============================

malloc() size overflow, upstream patch (revised by the developers):

https://github.com/ivmai/bdwgc/commit/be9df82919960214ee4b9d3313523bff44fd99e1

The bug in mallocx.c was found by Ivan Maidanski.

calloc() size overflow, upstream patch (revised by the developers):

https://github.com/ivmai/bdwgc/commit/e10c1eb9908c2774c16b3148b30d2f3823d66a9a
https://github.com/ivmai/bdwgc/commit/6a93f8e5bcad22137f41b6c60a1c7384baaec2b3
https://github.com/ivmai/bdwgc/commit/83231d0ab5ed60015797c3d1ad9056295ac3b2bb


bionic (Android libc)
=====================

malloc() size overflow, upstream patch (revised by the developers):

https://github.com/android/platform_bionic/commit/7f5aa4f35e23fd37425b3a5041737cdf58f87385

NB: this vulnerability could only be triggered in debug mode, the
same as CVE-2009-0607, calloc() size overflow.


nedmalloc
=========

malloc() size overflow, upstream patch:

https://github.com/ned14/nedmalloc/commit/1a759756639ab7543b650a10c2d77a0ffc7a2000

calloc() size overflow, upstream patch:

https://github.com/ned14/nedmalloc/commit/2965eca30c408c13473c4146a9d47d547d288db1


Hoard
=====

http://www.hoard.org/

malloc() size overflow, confirmed by the developers via email in
this March, no upstream patch available (since 3.8).

calloc() size overflow, which should only happen on non-glibc
platforms (e.g., Mac OS X).  It has not been confirmed by the
developers, but one can easily reproduce it.


boost::pool
===========

ordered_malloc() (similar to calloc()) size overflow, upstream patch:

https://svn.boost.org/trac/boost/changeset/78326


- xi

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