From: wen.yang@linux.dev
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org, linux-kernel@vger.kernel.org,
Deepak Kumar Singh <quic_deesin@quicinc.com>,
Bjorn Andersson <andersson@kernel.org>,
Wen Yang <wen.yang@linux.dev>
Subject: [PATCH 6.1] rpmsg: char: Add lock to avoid race when rpmsg device is released
Date: Wed, 17 Jun 2026 23:24:18 +0800 [thread overview]
Message-ID: <20260617152418.7046-1-wen.yang@linux.dev> (raw)
From: Deepak Kumar Singh <quic_deesin@quicinc.com>
commit 17b88a2050e9d1f89a53562f2adb709a8959e763 upstream.
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>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/1663584840-15762-2-git-send-email-quic_deesin@quicinc.com
Signed-off-by: Wen Yang <wen.yang@linux.dev>
---
drivers/rpmsg/rpmsg_char.c | 8 ++++++++
1 file changed, 8 insertions(+)
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;
}
--
2.34.1
reply other threads:[~2026-06-17 15:24 UTC|newest]
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