Input: powermate - fix oops with malicious USB descriptors

The powermate driver expects at least one valid USB endpoint in its
probe function.  If given malicious descriptors that specify 0 for
the number of endpoints, it will crash.  Validate the number of
endpoints on the interface before using them.

The full report for this issue can be found here:
http://seclists.org/bugtraq/2016/Mar/85

Reported-by: Ralf Spenneberg <ralf@spenneberg.net>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Josh Boyer <jwboyer@fedoraproject.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/misc/powermate.c b/drivers/input/misc/powermate.c
index 63b539d3dabae13ce7d1cb12fe19322f655043fd..84909a12ff36c231e7bcfc545bc2ce180c6cd26f 100644 (file)
--- a/drivers/input/misc/powermate.c
+++ b/drivers/input/misc/powermate.c
@@ -307,6 +307,9 @@ static int powermate_probe(struct usb_interface *intf, const struct usb_device_i
        int error = -ENOMEM;
 
        interface = intf->cur_altsetting;
+       if (interface->desc.bNumEndpoints < 1)
+               return -EINVAL;
+
        endpoint = &interface->endpoint[0].desc;
        if (!usb_endpoint_is_int_in(endpoint))
                return -EIO;