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

[Johan Hovold <johan@kernel.org>]

On Thu, Mar 26, 2020 at 09:21:17AM +0100, Johan Hovold wrote:
> 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@syzkaller.appspotmail.com
> > > Signed-off-by: Qiujun Huang <hqjagain@gmail.com>
> > > ---
> > >  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.

This issue predates git so I'd add

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Acked-by: Johan Hovold <johan@kernel.org>

if you want to take it yourself. Just let me know, otherwise I'll
include in my PR.

Johan