Call to rpmsg_ctrldev_ioctl() and rpmsg_ctrldev_remove() must be synchronized. In present code rpmsg_ctrldev_remove() is not protected with lock, therefore new char device creation can succeed through rpmsg_ctrldev_ioctl() call. At the same time call to rpmsg_ctrldev_remove() function for ctrl device removal will free associated rpdev device. As char device creation already succeeded, user space is free to issue open() call which maps to rpmsg_create_ept() in kernel. rpmsg_create_ept() function tries to reference rpdev which has already been freed through rpmsg_ctrldev_remove(). Issue is predominantly seen in aggressive reboot tests where rpmsg_ctrldev_ioctl() and rpmsg_ctrldev_remove() can race with each other. Adding lock in rpmsg_ctrldev_remove() avoids any new char device creation through rpmsg_ctrldev_ioctl() while remove call is already in progress. Signed-off-by: Deepak Kumar Singh <quic_deesin@xxxxxxxxxxx> --- drivers/rpmsg/rpmsg_ctrl.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/rpmsg/rpmsg_ctrl.c b/drivers/rpmsg/rpmsg_ctrl.c index 107da70..4332538 100644 --- a/drivers/rpmsg/rpmsg_ctrl.c +++ b/drivers/rpmsg/rpmsg_ctrl.c @@ -194,10 +194,12 @@ static void rpmsg_ctrldev_remove(struct rpmsg_device *rpdev) struct rpmsg_ctrldev *ctrldev = dev_get_drvdata(&rpdev->dev); int ret; + mutex_lock(&ctrldev->ctrl_lock); /* Destroy all endpoints */ ret = device_for_each_child(&ctrldev->dev, NULL, rpmsg_chrdev_eptdev_destroy); if (ret) dev_warn(&rpdev->dev, "failed to nuke endpoints: %d\n", ret); + mutex_unlock(&ctrldev->ctrl_lock); cdev_device_del(&ctrldev->cdev, &ctrldev->dev); put_device(&ctrldev->dev); -- 2.7.4
