[RFT] [media] siano: FIX use-after-free in worker_thread

[Arvind Yadav]

If CONFIG_MEDIA_CONTROLLER_DVB is enable, We are not releasing
media device and memory on any failure or disconnect a device.

Adding structure media_device 'mdev' as part of 'smsusb_device_t'
structure to make proper handle for media device.
Now releasing a media device and memory on failure. It's allocate
first in siano_media_device_register() and it should be freed last
in smsusb_disconnect().

Signed-off-by: Arvind Yadav <arvind.yadav...@gmail.com>
---
This bug report by Andrey Konovalov "usb/media/smsusb: use-after-free in
worker_thread".

 drivers/media/usb/siano/smsusb.c | 45 ++++++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 18 deletions(-)

diff --git a/drivers/media/usb/siano/smsusb.c b/drivers/media/usb/siano/smsusb.c
index 8c1f926..66936b3 100644
--- a/drivers/media/usb/siano/smsusb.c
+++ b/drivers/media/usb/siano/smsusb.c
@@ -69,6 +69,9 @@ struct smsusb_device_t {
        unsigned char in_ep;
        unsigned char out_ep;
        enum smsusb_state state;
+#ifdef CONFIG_MEDIA_CONTROLLER_DVB
+       struct media_device *mdev;
+#endif
 };
 
 static int smsusb_submit_urb(struct smsusb_device_t *dev,
@@ -359,6 +362,13 @@ static void smsusb_term_device(struct usb_interface *intf)
                if (dev->coredev)
                        smscore_unregister_device(dev->coredev);
 
+#ifdef CONFIG_MEDIA_CONTROLLER_DVB
+               if (dev->mdev) {
+                       media_device_unregister(dev->mdev);
+                       media_device_cleanup(dev->mdev);
+                       kfree(dev->mdev);
+               }
+#endif
                pr_debug("device 0x%p destroyed\n", dev);
                kfree(dev);
        }
@@ -370,27 +380,28 @@ static void *siano_media_device_register(struct 
smsusb_device_t *dev,
                                        int board_id)
 {
 #ifdef CONFIG_MEDIA_CONTROLLER_DVB
-       struct media_device *mdev;
        struct usb_device *udev = dev->udev;
        struct sms_board *board = sms_get_board(board_id);
        int ret;
 
-       mdev = kzalloc(sizeof(*mdev), GFP_KERNEL);
-       if (!mdev)
+       dev->mdev = kzalloc(sizeof(*dev->mdev), GFP_KERNEL);
+       if (!dev->mdev)
                return NULL;
 
-       media_device_usb_init(mdev, udev, board->name);
 
-       ret = media_device_register(mdev);
+       media_device_usb_init(dev->mdev, udev, board->name);
+
+       ret = media_device_register(dev->mdev);
        if (ret) {
-               media_device_cleanup(mdev);
-               kfree(mdev);
+               media_device_cleanup(dev->mdev);
+               kfree(dev->mdev);
+               dev->mdev = NULL;
                return NULL;
        }
 
        pr_info("media controller created\n");
 
-       return mdev;
+       return dev->mdev;
 #else
        return NULL;
 #endif
@@ -458,12 +469,7 @@ static int smsusb_init_device(struct usb_interface *intf, 
int board_id)
        rc = smscore_register_device(&params, &dev->coredev, mdev);
        if (rc < 0) {
                pr_err("smscore_register_device(...) failed, rc %d\n", rc);
-               smsusb_term_device(intf);
-#ifdef CONFIG_MEDIA_CONTROLLER_DVB
-               media_device_unregister(mdev);
-#endif
-               kfree(mdev);
-               return rc;
+               goto err_smsusb_init;
        }
 
        smscore_set_board_id(dev->coredev, board_id);
@@ -480,8 +486,7 @@ static int smsusb_init_device(struct usb_interface *intf, 
int board_id)
        rc = smsusb_start_streaming(dev);
        if (rc < 0) {
                pr_err("smsusb_start_streaming(...) failed\n");
-               smsusb_term_device(intf);
-               return rc;
+               goto err_smsusb_init;
        }
 
        dev->state = SMSUSB_ACTIVE;
@@ -489,13 +494,17 @@ static int smsusb_init_device(struct usb_interface *intf, 
int board_id)
        rc = smscore_start_device(dev->coredev);
        if (rc < 0) {
                pr_err("smscore_start_device(...) failed\n");
-               smsusb_term_device(intf);
-               return rc;
+               goto err_smsusb_init;
        }
 
        pr_debug("device 0x%p created\n", dev);
 
        return rc;
+
+err_smsusb_init:
+       smsusb_term_device(intf);
+
+       return rc;
 }
 
 static int smsusb_probe(struct usb_interface *intf,
-- 
1.9.1