Re: [PATCH] media:usb:cpia2: Properly check framebuffer mmap offsets

[Greg Kroah-Hartman]

On Sat, Nov 09, 2019 at 12:39:43PM +0100, Hans Verkuil wrote:
> Hi Greg,
> 
> On 11/8/19 9:49 PM, Greg Kroah-Hartman wrote:
> > On Fri, Nov 08, 2019 at 09:50:36PM +0000, Omer Shalev wrote:
> >> The cpai2 driver's mmap implementation wasn't properly check for all
> >> possible offset values. Given a huge offset value , the calculation
> >> start_offset + size can wrap around to a low value and pass the check
> > 
> > I thought we checked that in the core of the kernel now, to keep all
> > drivers from not having to do this type of thing (as they obviously all
> > forgot to.)  Why is this still needed here as well?
> 
> Where is that checked in the core? I couldn't find anything, but I might
> have been looking in the wrong place.

Sorry, took me a while to find it.  Look at be83bbf80682 ("mmap:
introduce sane default mmap limits") as I think this should handle the
problem already.

thanks,

greg k-h