From: Kees Cook <keescook@chromium.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Laura Abbott <labbott@redhat.com>,
kernel-hardening@lists.openwall.com,
LKML <linux-kernel@vger.kernel.org>,
Mark Rutland <mark.rutland@arm.com>, X86 ML <x86@kernel.org>
Subject: Re: [RFC PATCH 2/2] x86: Allow paranoid __{get,put}_user
Date: Fri, 3 Nov 2017 18:41:48 -0700 [thread overview]
Message-ID: <CAGXu5jKw-=hQUgPUd5E9Rgt-mSD+aDWBDfyJdKbu6xCOzM5p5g@mail.gmail.com> (raw)
In-Reply-To: <CAGXu5j+6Q+=2NoXmDJPO3wWGH8nDkHuGujKVgH6fb8cqkHq7WQ@mail.gmail.com>
On Fri, Nov 3, 2017 at 6:39 PM, Kees Cook <keescook@chromium.org> wrote:
> On Fri, Nov 3, 2017 at 5:24 PM, Al Viro <viro@zeniv.linux.org.uk> wrote:
>> On Fri, Nov 03, 2017 at 05:14:05PM -0700, Kees Cook wrote:
>>> > x86 turns out to be easier since the safe and unsafe paths are mostly
>>> > disjoint so we don't have to worry about gcc optimizing out access_ok.
>>> > I tweaked the Kconfig to someting a bit more generic.
>>> >
>>> > The size increase was ~8K in text with a config I tested.
>>>
>>> Specifically, this feature would have caught the waitid() bug in 4.13
>>> immediately.
>>
>> You mean, as soon as waitid() was given a kernel address. At which point
>> you'd get a shiny way to generate a BUG(), and if something like that
>> happened under a mutex - it's even more fun...
>
> Nope, any usage at all would BUG. This would have been immediately noticed. :)
Sorry, ignore that; yes, on any kernel address. But as always
reduction of impact is important: from exploitable flaw to DoS. Much
better!
-Kees
--
Kees Cook
Pixel Security
next prev parent reply other threads:[~2017-11-04 1:41 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-26 9:09 [RFC PATCH 0/2] arm64: optional paranoid __{get,put}_user checks Mark Rutland
2017-10-26 9:09 ` [RFC PATCH 1/2] arm64: write __range_ok() in C Mark Rutland
2017-11-16 15:28 ` Will Deacon
2017-11-20 12:22 ` Mark Rutland
2017-10-26 9:09 ` [RFC PATCH 2/2] arm64: allow paranoid __{get,put}user Mark Rutland
2017-10-27 15:41 ` [RFC PATCH 0/2] arm64: optional paranoid __{get,put}_user checks Will Deacon
2017-10-27 20:44 ` Mark Rutland
2017-10-28 8:47 ` Russell King - ARM Linux
2017-10-31 23:56 ` Laura Abbott
2017-11-01 12:05 ` Mark Rutland
2017-11-01 21:13 ` Laura Abbott
2017-11-01 22:28 ` Kees Cook
2017-11-01 23:05 ` Laura Abbott
2017-11-01 23:29 ` Kees Cook
2017-11-02 1:25 ` Laura Abbott
2017-11-03 23:04 ` [RFC PATCH 1/2] x86: Avoid multiple evaluations in __{get,put}_user_size Laura Abbott
2017-11-03 23:04 ` [RFC PATCH 2/2] x86: Allow paranoid __{get,put}_user Laura Abbott
2017-11-04 0:14 ` Kees Cook
2017-11-04 0:24 ` Al Viro
2017-11-04 0:44 ` Al Viro
2017-11-04 1:39 ` Kees Cook
2017-11-04 1:41 ` Kees Cook [this message]
2017-11-04 1:58 ` Mark Rutland
2017-11-06 20:38 ` Laura Abbott
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAGXu5jKw-=hQUgPUd5E9Rgt-mSD+aDWBDfyJdKbu6xCOzM5p5g@mail.gmail.com' \
--to=keescook@chromium.org \
--cc=kernel-hardening@lists.openwall.com \
--cc=labbott@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=viro@zeniv.linux.org.uk \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).