Follow @Openwall on Twitter for new release announcements and other news
[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Date: Tue, 13 Sep 2016 08:02:56 +1000
From: Brian May <brian@...uxpenguins.xyz>
To: oss-security@...ts.openwall.com
Subject: Re: autotrace: out-of-bounds write

Agostino Sarubbo <ago@...too.org> writes:

> with Address Sanitizer I found that each bmp you try to manage with autotrace 
> causes an out-of-bounds write.
>
> Details:
> https://blogs.gentoo.org/ago/2016/09/10/autotrace-heap-based-buffer-overflow-in-pstoedit_suffix_table_init-output-pstoedit-c/

I have had a look at CVE-2016-7392 in autotrace, in Debian wheezy. From
a quick glance at source code, the code does:

XMALLOC(pstoedit_suffix_table, sizeof(char *) * 2 * (dd_tmp - dd_start) + 1);

Which I believe is the same as:

XMALLOC(pstoedit_suffix_table, (sizeof(char *) * 2 * (dd_tmp - dd_start)) + 1);

i.e. the code leaves room for one byte at the end. However we store a
(char *) at the very end. Which I think might be more then one byte:

pstoedit_suffix_table[2 * (dd_tmp - dd_start)] = NULL;

My testing indicates the problem goes away if you change the line to:

XMALLOC(pstoedit_suffix_table, sizeof(char *) * (2 * (dd_tmp - dd_start) + 1));
-- 
Brian May <brian@...uxpenguins.xyz>
https://linuxpenguins.xyz/brian/

Powered by blists - more mailing lists

Please check out the Open Source Software Security Wiki, which is counterpart to this mailing list.

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.