[PATCH] usb_driver_claim_interface: add sanity checking

[PATCH] usb_driver_claim_interface: add sanity checking

[Oliver Neukum]

Attacks that trick drivers into passing a NULL pointer
to usb_driver_claim_interface() using forged descriptors are
known. This thwarts them by sanity checking.

Signed-off-by: Oliver Neukum <ONeukum@suse.com>
CC: stable@vger.kernel.org
---
 drivers/usb/core/driver.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/usb/core/driver.c b/drivers/usb/core/driver.c
index 56593a9..2057d91 100644
--- a/drivers/usb/core/driver.c
+++ b/drivers/usb/core/driver.c
@@ -502,11 +502,15 @@ static int usb_unbind_interface(struct device *dev)
 int usb_driver_claim_interface(struct usb_driver *driver,
 				struct usb_interface *iface, void *priv)
 {
-	struct device *dev = &iface->dev;
+	struct device *dev;
 	struct usb_device *udev;
 	int retval = 0;
 	int lpm_disable_error;
 
+	if (!iface)
+		return -ENODEV;
+
+	dev = &iface->dev;
 	if (dev->driver)
 		return -EBUSY;
 
-- 
2.1.4

Re: [PATCH] usb_driver_claim_interface: add sanity checking

[Alan Stern]

On Wed, 16 Mar 2016, Oliver Neukum wrote:

> Attacks that trick drivers into passing a NULL pointer
> to usb_driver_claim_interface() using forged descriptors are
> known. This thwarts them by sanity checking.

I'm curious -- how do these attacks carry out their trickery?

Alan Stern

Re: [PATCH] usb_driver_claim_interface: add sanity checking

[Oliver Neukum]

On Wed, 2016-03-16 at 10:08 -0400, Alan Stern wrote:
> On Wed, 16 Mar 2016, Oliver Neukum wrote:
> 
> > Attacks that trick drivers into passing a NULL pointer
> > to usb_driver_claim_interface() using forged descriptors are
> > known. This thwarts them by sanity checking.
> 
> I'm curious -- how do these attacks carry out their trickery?

They are using a programmable gadget.
http://seclists.org/bugtraq/2016/Mar/90

	HTH
		Oliver