Re: [PATCH] Input :Added Check for EV_ABS event params

[Peter Hutterer <peter.hutterer@who-t.net>]

On Tue, Apr 21, 2015 at 11:29:16AM -0700, Dmitry Torokhov wrote:
> Hi Anshul,
> 
> On Tue, Apr 21, 2015 at 11:19:52AM -0700, Anshul Garg wrote:
> > From: Anshul Garg <aksgarg1989@gmail.com>
> > 
> > while handling EV_ABS event in input_handle_abs_event
> > function added check for out of range event value from
> > input driver. As input driver sets the ABS params at
> > registration time so input core should ignore events out
> > of the range set by the input driver.
> 
> No, I do not think we want to do that, at least not unconditionally,
> especially since it is perfectly allowed to use 0 as min/max, which
> means that exact min and max are not defined. Historically min and max
> were provided to the userspace as a guidance and it was up to userspace
> to decide what to do with values outside of the limits.

for the archives:
X requires us to drop coordinates outside the given range, at least the 
ones we forward to the clients from absolute devices. We have used
out-of-bounds variables within the synaptics driver in the past though.

Cheers,
   Peter

> > 
> > Signed-off-by: Anshul Garg <aksgarg1989@gmail.com>
> > ---
> >  drivers/input/input.c |    5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > diff --git a/drivers/input/input.c b/drivers/input/input.c
> > index cc357f1..b1a6ff6 100644
> > --- a/drivers/input/input.c
> > +++ b/drivers/input/input.c
> > @@ -244,6 +244,11 @@ static int input_handle_abs_event(struct input_dev *dev,
> >  		pold = NULL;
> >  	}
> >  
> > +	if (dev->absinfo[code].minimum > *pval || dev->absinfo[code].maximum < *pval) {
> > +		/* Ignore event with out of range values */		
> > +		return INPUT_IGNORE_EVENT;
> > +	}
> > +
> >  	if (pold) {
> >  		*pval = input_defuzz_abs_event(*pval, *pold,
> >  						dev->absinfo[code].fuzz);
> > -- 
> > 1.7.9.5
> >