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Groups > linux.kernel > #1599327 > unrolled thread

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

Started byJohan Hovold <johan@kernel.org>
First post2017-03-13 14:00 +0100
Last post2017-03-13 18:20 +0100
Articles 5 — 2 participants

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  [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

#1599327 — [PATCH] watchdog: pcwd_usb: fix NULL-deref at probe

FromJohan Hovold <johan@kernel.org>
Date2017-03-13 14:00 +0100
Subject[PATCH] watchdog: pcwd_usb: fix NULL-deref at probe
Message-ID<tkxJU-Fd-25@gated-at.bofh.it>
Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer should a malicious device lack endpoints.

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;
 
-- 
2.12.0

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#1599373

FromGuenter Roeck <linux@roeck-us.net>
Date2017-03-13 14:50 +0100
Message-ID<tkywi-1es-25@gated-at.bofh.it>
In reply to#1599327
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 ?

Thanks,
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;
>
>

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#1599412

FromJohan Hovold <johan@kernel.org>
Date2017-03-13 15:20 +0100
Message-ID<tkyZk-1HR-13@gated-at.bofh.it>
In reply to#1599373
[ 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.

> > 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

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#1599646

FromGuenter Roeck <linux@roeck-us.net>
Date2017-03-13 18:20 +0100
Message-ID<tkBNv-3I1-13@gated-at.bofh.it>
In reply to#1599412
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

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#1599645

FromGuenter Roeck <linux@roeck-us.net>
Date2017-03-13 18:20 +0100
Message-ID<tkBNv-3I1-11@gated-at.bofh.it>
In reply to#1599327
On Mon, Mar 13, 2017 at 01:49:45PM +0100, Johan Hovold wrote:
> Make sure to check the number of endpoints to avoid dereferencing a
> NULL-pointer should a malicious device lack endpoints.
> 
> Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
> Cc: stable <stable@vger.kernel.org>
> Signed-off-by: Johan Hovold <johan@kernel.org>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

Note that I dropped Cc: stable from my reply since it is not appropriate
at this time.

Guenter

> ---
>  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;
>  
> -- 
> 2.12.0
>

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