drivers/media/media-devnode: clear private_data before put_device()

BugLink: https://bugs.launchpad.net/bugs/1883916

commit bf244f66 upstream.

Callbacks invoked from put_device() may free the struct media_devnode
pointer, so any cleanup needs to be done before put_device().
Signed-off-by: Max Kellermann <max@duempel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/media/media-devnode.c

@@ -197,10 +197,11 @@ static int media_release(struct inode *inode, struct file *filp)
 	if (mdev->fops->release)
 		mdev->fops->release(filp);
 
+	filp->private_data = NULL;
+
 	/* decrease the refcount unconditionally since the release()
 	   return value is ignored. */
 	put_device(&mdev->dev);
-	filp->private_data = NULL;
 	return 0;
 }