From: Wolfram Gloger <wg@malloc.de>
To: Kees Cook <kees@outflux.net>
Cc: dvyukov@google.com, ak@linux.intel.com,
linux-kernel@vger.kernel.org, pjt@google.com,
andreyknvl@google.com, kcc@google.com, x86@kernel.org
Subject: Re: Out-of-bounds access in get_wchan (arch/x86/kernel/process_64.c)
Date: Sat, 28 Sep 2013 21:51:14 +0200 [thread overview]
Message-ID: <u4zjqwg1xp.fsf@mail.malloc.de> (raw)
In-Reply-To: <20130927190312.GV21253@outflux.net> (message from Kees Cook on Fri, 27 Sep 2013 12:03:12 -0700)
Kees Cook <kees@outflux.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.
next prev parent reply other threads:[~2013-09-28 19:51 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-03 14:41 Out-of-bounds access in get_wchan (arch/x86/kernel/process_64.c) Dmitry Vyukov
2013-09-10 22:06 ` Andi Kleen
2013-09-11 18:16 ` Dmitry Vyukov
2013-09-27 19:03 ` Kees Cook
2013-09-28 19:51 ` Wolfram Gloger [this message]
2013-09-28 21:01 ` Kees Cook
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