USB: uss720: fix NULL-deref at probe
authorJohan Hovold <johan@kernel.org>
Mon, 13 Mar 2017 12:47:50 +0000 (13:47 +0100)
committerBen Hutchings <ben@decadent.org.uk>
Tue, 18 Jul 2017 17:38:32 +0000 (18:38 +0100)
commit f259ca3eed6e4b79ac3d5c5c9fb259fb46e86217 upstream.

Make sure to check the number of endpoints to avoid dereferencing a
NULL-pointer or accessing memory beyond the endpoint array should a
malicious device lack the expected endpoints.

Note that the endpoint access that causes the NULL-deref is currently
only used for debugging purposes during probe so the oops only happens
when dynamic debugging is enabled. This means the driver could be
rewritten to continue to accept device with only two endpoints, should
such devices exist.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
drivers/usb/misc/uss720.c

index 8b1d94a..42396aa 100644 (file)
@@ -704,6 +704,11 @@ static int uss720_probe(struct usb_interface *intf,
 
        interface = intf->cur_altsetting;
 
+       if (interface->desc.bNumEndpoints < 3) {
+               usb_put_dev(usbdev);
+               return -ENODEV;
+       }
+
        /*
         * Allocate parport interface 
         */