From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, x86@kernel.org,
kirill.shutemov@linux.intel.com, shuah@kernel.org,
linux-kselftest@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH 1/2] x86, pkeys: check against max pkey to avoid overflows
Date: Fri, 24 Feb 2017 03:07:21 +0300 [thread overview]
Message-ID: <20170224000721.GA26920@node.shutemov.name> (raw)
In-Reply-To: <20170223222603.A022ED65@viggo.jf.intel.com>
On Thu, Feb 23, 2017 at 02:26:03PM -0800, Dave Hansen wrote:
>
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> Kirill got a warning from UBSAN about undefined behavior when using
> protection keys. He is running on hardware that actually has support
> for it, which is not widely available.
>
> The warning was because we did some very large shifts of integers when
> doing a pkey_free() of a large, invalid value because we never check
> that the pkey "fits" into the mm_pkey_allocation_map().
>
> I do not believe there is any danger here of anything bad happening
> other than some aliasing issues where somebody could do:
>
> pkey_free(35);
>
> and the kernel would effectively execute:
>
> pkey_free(8);
>
> While this might be confusing to an app that was doing something
> stupid, it has to do something stupid and the effects are limited to
> the app shooting itself in the foot.
>
> Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
--
Kirill A. Shutemov
next prev parent reply other threads:[~2017-02-24 0:08 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-23 22:26 [PATCH 1/2] x86, pkeys: check against max pkey to avoid overflows Dave Hansen
2017-02-23 22:26 ` [PATCH 2/2] selftests, x86, pkeys: test with random, unallocated protection keys Dave Hansen
2017-02-23 22:36 ` Shuah Khan
2017-02-24 7:45 ` Ingo Molnar
2017-02-24 14:41 ` Shuah Khan
2017-02-25 9:10 ` Ingo Molnar
2017-02-24 0:10 ` Kirill A. Shutemov
2017-02-24 0:07 ` Kirill A. Shutemov [this message]
2017-03-01 9:57 ` [tip:x86/urgent] x86/pkeys: Check against max pkey to avoid overflows tip-bot for Dave Hansen
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=20170224000721.GA26920@node.shutemov.name \
--to=kirill@shutemov.name \
--cc=dave.hansen@linux.intel.com \
--cc=kirill.shutemov@linux.intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-kselftest@vger.kernel.org \
--cc=shuah@kernel.org \
--cc=stable@vger.kernel.org \
--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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.