media: dvb-usb: Fix use-after-free access

dvb_usb_device_init() copies the properties to the own data, so that
the callers can release the original properties later (as done in the
commit 299c7007e936 ("media: dw2102: Fix memleak on sequence of
probes")).  However, it also stores dev->desc pointer that is a
reference to the original properties data.  Since dev->desc is
referred later, it may result in use-after-free, in the worst case,
leading to a kernel Oops as reported.

This patch addresses the problem by allocating and copying the
properties at first, then get the desc from the copied properties.

Reported-and-tested-by: Stefan Seyfried <seife+kernel@b1-systems.com>
BugLink: http://bugzilla.opensuse.org/show_bug.cgi?id=1181104
Reviewed-by: Robert Foss <robert.foss@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

diff --git a/drivers/media/usb/dvb-usb/dvb-usb-init.c b/drivers/media/usb/dvb-usb/dvb-usb-init.c
index c78158d..6c9e329 100644 (file)
--- a/drivers/media/usb/dvb-usb/dvb-usb-init.c
+++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c
@@ -264,27 +264,30 @@ int dvb_usb_device_init(struct usb_interface *intf,
        if (du != NULL)
                *du = NULL;
 
-       if ((desc = dvb_usb_find_device(udev, props, &cold)) == NULL) {
+       d = kzalloc(sizeof(*d), GFP_KERNEL);
+       if (!d) {
+               err("no memory for 'struct dvb_usb_device'");
+               return -ENOMEM;
+       }
+
+       memcpy(&d->props, props, sizeof(struct dvb_usb_device_properties));
+
+       desc = dvb_usb_find_device(udev, &d->props, &cold);
+       if (!desc) {
                deb_err("something went very wrong, device was not found in current device list - let's see what comes next.\n");
-               return -ENODEV;
+               ret = -ENODEV;
+               goto error;
        }
 
        if (cold) {
                info("found a '%s' in cold state, will try to load a firmware", desc->name);
                ret = dvb_usb_download_firmware(udev, props);
                if (!props->no_reconnect || ret != 0)
-                       return ret;
+                       goto error;
        }
 
        info("found a '%s' in warm state.", desc->name);
-       d = kzalloc(sizeof(struct dvb_usb_device), GFP_KERNEL);
-       if (d == NULL) {
-               err("no memory for 'struct dvb_usb_device'");
-               return -ENOMEM;
-       }
-
        d->udev = udev;
-       memcpy(&d->props, props, sizeof(struct dvb_usb_device_properties));
        d->desc = desc;
        d->owner = owner;