Re: [PATCH] watchdog: pcwd_usb: fix NULL-deref at probe

From	Guenter Roeck <linux@roeck-us.net>
Newsgroups	linux.kernel
Subject	Re: [PATCH] watchdog: pcwd_usb: fix NULL-deref at probe
Date	2017-03-13 18:20 +0100
Message-ID	<tkBNv-3I1-13@gated-at.bofh.it> (permalink)
References	<tkxJU-Fd-25@gated-at.bofh.it> <tkywi-1es-25@gated-at.bofh.it> <tkyZk-1HR-13@gated-at.bofh.it>
Organization	linux.* mail to news gateway

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On Mon, Mar 13, 2017 at 03:17:39PM +0100, Johan Hovold wrote:
> [ Adding linux-usb which I forgot to CC for this one ]
> 
> On Mon, Mar 13, 2017 at 06:42:45AM -0700, Guenter Roeck wrote:
> > On 03/13/2017 05:49 AM, Johan Hovold wrote:
> > > Make sure to check the number of endpoints to avoid dereferencing a
> > > NULL-pointer should a malicious device lack endpoints.
> > >
> > 
> > Is this theory or was it actually observed ?
> 
> This was found through inspection, but creating a USB device to crash a
> host with this driver enabled is easily done.
> 
Ok, makes sense. I see other drivers doing a similar check.

Guenter

> > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> > > Cc: stable <stable@vger.kernel.org>
> > > Signed-off-by: Johan Hovold <johan@kernel.org>
> > > ---
> > >  drivers/watchdog/pcwd_usb.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > >
> > > diff --git a/drivers/watchdog/pcwd_usb.c b/drivers/watchdog/pcwd_usb.c
> > > index 99ebf6ea3de6..5615f4013924 100644
> > > --- a/drivers/watchdog/pcwd_usb.c
> > > +++ b/drivers/watchdog/pcwd_usb.c
> > > @@ -630,6 +630,9 @@ static int usb_pcwd_probe(struct usb_interface *interface,
> > >  		return -ENODEV;
> > >  	}
> > >
> > > +	if (iface_desc->desc.bNumEndpoints < 1)
> > > +		return -ENODEV;
> > > +
> > >  	/* check out the endpoint: it has to be Interrupt & IN */
> > >  	endpoint = &iface_desc->endpoint[0].desc;
> > >
> > >
> 
> Johan

Thread

[PATCH] watchdog: pcwd_usb: fix NULL-deref at probe Johan Hovold <johan@kernel.org> - 2017-03-13 14:00 +0100
  Re: [PATCH] watchdog: pcwd_usb: fix NULL-deref at probe Guenter Roeck <linux@roeck-us.net> - 2017-03-13 14:50 +0100
    Re: [PATCH] watchdog: pcwd_usb: fix NULL-deref at probe Johan Hovold <johan@kernel.org> - 2017-03-13 15:20 +0100
      Re: [PATCH] watchdog: pcwd_usb: fix NULL-deref at probe Guenter Roeck <linux@roeck-us.net> - 2017-03-13 18:20 +0100
  Re: [PATCH] watchdog: pcwd_usb: fix NULL-deref at probe Guenter Roeck <linux@roeck-us.net> - 2017-03-13 18:20 +0100

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