From: Scott Wood <scottwood@freescale.com>
To: Alexander Graf <agraf@suse.de>
Cc: Liu Yu <yu.liu@freescale.com>,
qemu-ppc@nongnu.org,
qemu-devel Developers <qemu-devel@nongnu.org>
Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH] ppc/e500_pci: Fix an array overflow issue
Date: Tue, 27 Sep 2011 12:06:15 -0500 [thread overview]
Message-ID: <4E820287.1090805@freescale.com> (raw)
In-Reply-To: <A1A73068-528D-4914-96A8-768A33E3CDD2@suse.de>
On 09/27/2011 12:01 PM, Alexander Graf wrote:
>
> On 27.09.2011, at 18:52, Scott Wood wrote:
>
>> On 09/27/2011 07:45 AM, Alexander Graf wrote:
>>> So this is the main change, right? Why the -1? A guest could potentially access pib[-1] using this, no?
>>
>> Not with the values of addr that lead to this code. The -1 is because
>> IW1/2/3 are 0x1e0/0x1c0/0x1a0. Previously IW1 would overflow the array.
>
> We're matching on addr & 0xfe0 and do the switch based on that. Possible values are:
>
> 0x1a0
> 0x1c0
> 0x1e0
>
> Then we >> 5 them.
>
> 0xd
> 0xe
> 0xf
>
> ... and & 0x3 them
>
> 0x1
> 0x2
> 0x0
0xd & 0x3 = 1
0xe & 0x3 = 2
0xf & 0x3 = 3
-Scott
prev parent reply other threads:[~2011-09-27 17:07 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-27 8:17 [Qemu-devel] [PATCH] ppc/e500_pci: Fix an array overflow issue Liu Yu
2011-09-27 12:45 ` Alexander Graf
2011-09-27 16:52 ` [Qemu-devel] [Qemu-ppc] " Scott Wood
2011-09-27 17:01 ` Alexander Graf
2011-09-27 17:04 ` Richard Henderson
2011-09-27 17:04 ` Alexander Graf
2011-09-27 17:06 ` Scott Wood [this message]
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=4E820287.1090805@freescale.com \
--to=scottwood@freescale.com \
--cc=agraf@suse.de \
--cc=qemu-devel@nongnu.org \
--cc=qemu-ppc@nongnu.org \
--cc=yu.liu@freescale.com \
/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.