linux-kernel - Re: Out-of-bounds access in get_wchan (arch/x86/kernel/process

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <u4zjqwg1xp.fsf@mail.malloc.de>
Date:	Sat, 28 Sep 2013 21:51:14 +0200
From:	Wolfram Gloger <wg@...loc.de>
To:	Kees Cook <kees@...flux.net>
Cc:	dvyukov@...gle.com, ak@...ux.intel.com,
	linux-kernel@...r.kernel.org, pjt@...gle.com,
	andreyknvl@...gle.com, kcc@...gle.com, x86@...nel.org
Subject: Re: Out-of-bounds access in get_wchan (arch/x86/kernel/process_64.c)

Kees Cook <kees@...flux.net> writes:

> Please note that these bounds checks aren't correct to begin with. Since
> a pointer is being dereferenced, the end boundry must be reduced by
> sizeof(unsigned long) as well.
>
> It looks like process_32.c suffers the same problems, too.

I can't see the end boundary problem in process_32.c.  The end checks
are properly reduced with the top_esp and top_ebp macros.

All I can see in process_32.c is that the check

		if (bp < stack_page || bp > top_ebp+stack_page)

could be replaced by:

		if (bp < stack_page-sizeof(unsigned long) || bp > top_ebp+stack_page)

but that is a relaxation and not an over/underrun fix.

Can you elaborate what problem you see in process_32.c?

Regards,
Wolfram.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/