[PATCH 5.19 0907/1157] rpmsg: char: Add mutex protection for rpmsg_eptdev_open()

Greg Kroah-Hartman
2022-08-16T00:38:56Z

From: Shengjiu Wang <shengjiu.wang@nxp.com>

[ Upstream commit abe13e9a561d6b3e82b21362c0d6dd3ecd8a5b13 ]

There is no mutex protection for rpmsg_eptdev_open(),
especially for eptdev->ept read and write operation.
It may cause issues when multiple instances call
rpmsg_eptdev_open() in parallel,the return state
may be success or EBUSY.

Fixes: 964e8bedd5a1 ("rpmsg: char: Return an error if device already open")
Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1653104105-16779-1-git-send-email-shengjiu.wang@nxp.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/rpmsg/rpmsg_char.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
index b6183d4f62a2..4f2189111494 100644
--- a/drivers/rpmsg/rpmsg_char.c
+++ b/drivers/rpmsg/rpmsg_char.c
@@ -120,8 +120,11 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
struct rpmsg_device *rpdev = eptdev->rpdev;
struct device *dev = &eptdev->dev;

- if (eptdev->ept)
+ mutex_lock(&eptdev->ept_lock);
+ if (eptdev->ept) {
+ mutex_unlock(&eptdev->ept_lock);
return -EBUSY;
+ }

get_device(dev);

@@ -137,11 +140,13 @@ static int rpmsg_eptdev_open(struct inode *inode, struct file *filp)
if (!ept) {
dev_err(dev, "failed to open %s\n", eptdev->chinfo.name);
put_device(dev);
+ mutex_unlock(&eptdev->ept_lock);
return -EINVAL;
}

eptdev->ept = ept;
filp->private_data = eptdev;
+ mutex_unlock(&eptdev->ept_lock);

return 0;
}
--
2.35.1