[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Wed, 18 Jan 2012 12:43:28 -0800
From: Kees Cook <kees@...ntu.com>
To: oss-security@...ts.openwall.com
Cc: "Steven M. Christey" <coley@...us.mitre.org>
Subject: Re: CVE request: kernel: proc: clean up and fix
/proc/<pid>/mem handling
What's the problem with the old logic in the mem handling? (Why does this
need a CVE?)
On Wed, Jan 18, 2012 at 10:25:55AM +0800, Eugene Teo wrote:
> "Jüri Aedla reported that the /proc/<pid>/mem handling really isn't very
> robust, and it also doesn't match the permission checking of any of the
> other related files.
>
> This changes it to do the permission checks at open time, and instead of
> tracking the process, it tracks the VM at the time of the open. That
> simplifies the code a lot, but does mean that if you hold the file
> descriptor open over an execve(), you'll continue to read from the _old_ VM.
>
> That is different from our previous behavior, but much simpler. If
> somebody actually finds a load where this matters, we'll need to revert
> this commit.
>
> I suspect that nobody will ever notice - because the process mapping
> addresses will also have changed as part of the execve. So you cannot
> actually usefully access the fd across a VM change simply because all
> the offsets for IO would have changed too."
>
> http://git.kernel.org/linus/e268337dfe26dfc7efd422a804dbb27977a3cccc
>
> Thanks, Eugene
--
Kees Cook
Powered by blists - more mailing lists
Please check out the
Open Source Software Security Wiki, which is counterpart to this
mailing list.
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
