Re: [PATCH v3 2/3] rpmsg: char: Fix UAF and memory leak in rpmsg_anonymous_eptdev_create()

Mathieu Poirier
2025-11-14T19:01:47Z

On Thu, Nov 13, 2025 at 11:39:08PM +0800, Dawei Li wrote:
> Potential UAF and memory leak exsit in exception handling paths for
> rpmsg_anonymous_eptdev_create(), fix them.
>
> - If rpmsg_add_eptdev() failes, eptdev is freed in it.
> Subsequent call of dev_err(&eptdev->device) triggers a UAF.
> - If __rpmsg_eptdev_open() fails, eptdev is supposed to be freed by
> put_device().
>
> Fixes: 2410558f5f11 ("rpmsg: char: Implement eptdev based on anonymous inode")
> Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
> Closes: https://lore.kernel.org/all/aPi6gPZE2_ztOjIW@stanley.mountain/
> Signed-off-by: Dawei Li <dawei.li@linux.dev>
> ---
> drivers/rpmsg/rpmsg_char.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 1b8297b373f0..0919ad0a19df 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -494,6 +494,7 @@ static int rpmsg_eptdev_add(struct rpmsg_eptdev *eptdev,
> if (cdev)
> ida_free(&rpmsg_minor_ida, MINOR(dev->devt));
> free_eptdev:
> + dev_err(&eptdev->dev, "failed to add %s\n", eptdev->chinfo.name);
> kfree(eptdev);
>
> return ret;
> @@ -544,7 +545,6 @@ int rpmsg_anonymous_eptdev_create(struct rpmsg_device *rpdev, struct device *par
>
> ret = rpmsg_eptdev_add(eptdev, chinfo, false);
> if (ret) {
> - dev_err(&eptdev->dev, "failed to add %s\n", eptdev->chinfo.name);

This doesn't neet to be done if kfree(eptdev) is moved out of
rpmsg_eptdev_add().

> return ret;
> }
>
> @@ -560,6 +560,8 @@ int rpmsg_anonymous_eptdev_create(struct rpmsg_device *rpdev, struct device *par
>
> if (!ret)
> *pfd = fd;
> + else
> + put_device(&eptdev->dev);

This goes in the previous patch.

>
> return ret;
> }
> --
> 2.25.1
>