Re: [BUGFIX] NULL pointer dereference in __vm_enough_memory()

[WU Fengguang <wfg@mail.ustc.edu.cn>]

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 :)