From 17b88a2050e9d1f89a53562f2adb709a8959e763 Mon Sep 17 00:00:00 2001 From: Deepak Kumar Singh Date: Mon, 19 Sep 2022 16:23:59 +0530 Subject: 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: Deepak Kumar Singh Signed-off-by: Bjorn Andersson Link: https://lore.kernel.org/r/1663584840-15762-2-git-send-email-quic_deesin@quicinc.com --- drivers/rpmsg/rpmsg_char.c | 8 ++++++++ 1 file changed, 8 insertions(+) (limited to 'drivers/rpmsg') diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c index 3e0b8f3496ed..a271fceb16f4 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) { /* 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; } -- cgit v1.2.3