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Message-ID: <20070812140917.GA13683@mail.ustc.edu.cn>
Date: Sun, 12 Aug 2007 22:09:17 +0800
From: WU Fengguang <wfg@...l.ustc.edu.cn>
To: Alan Cox <alan@...rguk.ukuu.org.uk>
Cc: Balbir Singh <balbir@...ux.vnet.ibm.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Paul Moore <paul.moore@...com>,
Stephen Smalley <sds@...ch.ncsc.mil>,
Chris Vance <cvance@....com>, Wayne Salamon <wsalamon@....com>,
James Morris <jmorris@...hat.com>, dgoeddel@...stedcs.com
Subject: Re: [BUGFIX] NULL pointer dereference in __vm_enough_memory()
On Sun, Aug 12, 2007 at 02:19:05PM +0100, Alan Cox wrote:
> > > Great! So the problem might have existed for some time, but we never
> > > saw it due to default over commit values? Were you using these values
> > > for over commit even before?
> >
> > No I changed it several weeks ago to stop my desktop from freezing.
> > So yes, the bug may have been there for a while.
>
> The bug is the new exec with lots of arguments code. It tries to insert a
> vm struct without having a valid current->mm. That isn't permitted and
> never had been (which is also why it broke the sparc mmu code etc).
>
> You'll need to change the kernel security interface a little to make this
> fly - I think the following should do it.
>
> - make __vm_enough_memory take a struct mm pointer and use it
> - make security_ops pass the extra current->mm
> - add a vm_enough_memory_mm security op
> - use security_vm_enough_memory_mm(mm, ...) in __insert_vm_struct
>
> I'll knock up a quick patch and see what is needed (someone else can do
> the selinux changes)
Thank you!
Count me for one - but CC SELinux maintainers first :)
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