Re: [stable] please do not merge 058504edd026 (was Re: fs: use after free in /proc/pid/mountinfo)

From: Greg KH
Date: Mon Jul 07 2014 - 19:01:29 EST


On Fri, Jul 04, 2014 at 03:35:54PM -0700, David Rientjes wrote:
> On Fri, 4 Jul 2014, Sasha Levin wrote:
>
> > > Does this now reproduce on Linus's tree? If so, does reverting commit
> > > 058504edd026 ("fs/seq_file: fallback to vmalloc allocation") prevent this
> > > issue?
> > >
> > > This is a use-after-free since the poison value is 0x6b and I'm presuming
> > > that your /proc/self/mountinfo may be larger than PAGE_SIZE in your
> > > testing environment.
> > >
> >
> > Good call, reverting that patch made both issues go away.
> >
>
> Thanks for checking, Sasha.
>
> Stable maintainers, please do not merge commit 058504edd026 ("fs/seq_file:
> fallback to vmalloc allocation") that is annotated with a cc for
> stable@xxxxxxxxxxxxxxx in Linus's tree into stable kernels.
>
> Although we're at 3.16-rc3, I'm hoping that we can get a fix for the
> use-after-free in the next couple days before asking for a revert. Sasha
> confirms[*] this commit causes the bug.

I should also drop "Subject: /proc/stat: convert to single_open_size()"
from the -stable tree, right?

thanks,

greg k-h
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