diff mbox series

[V4,1/2] rpmsg: char: Add lock to avoid race when rpmsg device is released

Message ID 1663235055-3081-2-git-send-email-quic_deesin@quicinc.com
State Accepted
Commit 17b88a2050e9d1f89a53562f2adb709a8959e763
Headers show
Series rpmsg_char/ctrl driver fixes | expand

Commit Message

Deepak Kumar Singh Sept. 15, 2022, 9:44 a.m. UTC
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: Deepak Kumar Singh <quic_deesin@quicinc.com>
---
 drivers/rpmsg/rpmsg_char.c | 8 ++++++++
 1 file changed, 8 insertions(+)
diff mbox series

Patch

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index 4f21891..5500dc0 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -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) {
 		rpmsg_destroy_ept(eptdev->ept);
 		eptdev->ept = NULL;
@@ -126,6 +127,11 @@  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);
 
 	/*
@@ -277,7 +283,9 @@  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;
 }