Re: [PATCH] autofs4: check dev ioctl size before allocating

[Ian Kent <raven@themaw.net>]

On Sat, 2014-04-05 at 11:06 -0400, Sasha Levin wrote:
> Ping? Anyone wants to take this?

Is this causing a problem for users?
If it is I'll send it to Andrew straight away.

I do have this on my queue but don't have any other patches to send so
it's just sitting there.

If it worries you I'll send it to Andrew now.

> 
> On 03/15/2014 09:40 PM, Sasha Levin wrote:
> > There wasn't any check of the size passed from userspace before
> > trying to allocate the memory required.
> > 
> > This meant that userspace might request more space than allowed,
> > triggering an OOM.
> > 
> > Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> > ---
> >  fs/autofs4/dev-ioctl.c |    3 +++
> >  1 files changed, 3 insertions(+), 0 deletions(-)
> > 
> > diff --git a/fs/autofs4/dev-ioctl.c b/fs/autofs4/dev-ioctl.c
> > index 3182c0e..86fa7af 100644
> > --- a/fs/autofs4/dev-ioctl.c
> > +++ b/fs/autofs4/dev-ioctl.c
> > @@ -103,6 +103,9 @@ static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *i
> >  	if (tmp.size < sizeof(tmp))
> >  		return ERR_PTR(-EINVAL);
> >  
> > +	if (tmp.size > (PATH_MAX + sizeof(tmp)))
> > +		return ERR_PTR(-E2BIG);
> > +
> >  	return memdup_user(in, tmp.size);
> >  }
> >  
> > 
>