Commit 17b88a20 authored by Deepak Kumar Singh's avatar Deepak Kumar Singh Committed by Bjorn Andersson
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rpmsg: char: Add lock to avoid race when rpmsg device is released 



When remote host goes down glink char device channel is freed and
associated rpdev is destroyed through rpmsg_chrdev_eptdev_destroy(),
At the same time user space apps can still try to open/poll rpmsg
char device which will result in calling rpmsg_create_ept()/rpmsg_poll().
These functions will try to reference rpdev which has already been freed
through rpmsg_chrdev_eptdev_destroy().

File operation functions and device removal function must be protected
with lock. This patch adds existing ept lock in remove function as well.

Signed-off-by: default avatarDeepak Kumar Singh <quic_deesin@quicinc.com>
Signed-off-by: default avatarBjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/1663584840-15762-2-git-send-email-quic_deesin@quicinc.com
parent d2ff0f84

drivers/rpmsg/rpmsg_char.c

+8 −0
Original line number Diff line number Diff line
@@ -75,6 +75,7 @@ int rpmsg_chrdev_eptdev_destroy(struct device *dev, void *data) 
	struct rpmsg_eptdev *eptdev = dev_to_eptdev(dev);



	mutex_lock(&eptdev->ept_lock);

	eptdev->rpdev = NULL;

	if (eptdev->ept) {

		/* The default endpoint is released by the rpmsg core */

		if (!eptdev->default_ept)
@@ -128,6 +129,11 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp) 
		return -EBUSY;

	}



	if (!eptdev->rpdev) {

		mutex_unlock(&eptdev->ept_lock);

		return -ENETRESET;

	}



	get_device(dev);



	/*
@@ -279,7 +285,9 @@ static __poll_t rpmsg_eptdev_poll(struct file *filp, poll_table *wait) 
	if (!skb_queue_empty(&eptdev->queue))

		mask |= EPOLLIN | EPOLLRDNORM;



	mutex_lock(&eptdev->ept_lock);

	mask |= rpmsg_poll(eptdev->ept, filp, wait);

	mutex_unlock(&eptdev->ept_lock);



	return mask;

}