Re: [PATCH] USB: io_edgeport: fix slab-out-of-bounds Read in edge_interrupt_callback

[Johan Hovold]

On Thu, Mar 26, 2020 at 09:14:33AM +0100, Greg Kroah-Hartman wrote:
> On Wed, Mar 25, 2020 at 03:52:37PM +0800, Qiujun Huang wrote:
> > The boundary condition should be (length - 1) as we access data[position+1].
> > 
> > Reported-and-tested-by: syzbot+37ba33391ad5f3935bbd@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Signed-off-by: Qiujun Huang <hqjagain@xxxxxxxxx>
> > ---
> >  drivers/usb/serial/io_edgeport.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/usb/serial/io_edgeport.c b/drivers/usb/serial/io_edgeport.c
> > index 5737add..4cca0b8 100644
> > --- a/drivers/usb/serial/io_edgeport.c
> > +++ b/drivers/usb/serial/io_edgeport.c
> > @@ -710,7 +710,7 @@ static void edge_interrupt_callback(struct urb *urb)
> >  		/* grab the txcredits for the ports if available */
> >  		position = 2;
> >  		portNumber = 0;
> > -		while ((position < length) &&
> > +		while ((position < length - 1) &&
> >  				(portNumber < edge_serial->serial->num_ports)) {
> >  			txCredits = data[position] | (data[position+1] << 8);
> >  			if (txCredits) {
> > -- 
> > 1.8.3.1
> > 
> 
> Johan, any objection from me taking this in my tree now?

Just let me take a look at it first.

Are sending another PR to Linus for 5.6? Otherwise I can include this
in my 5.7 PR to you. Will try to get it to you today.

Johan