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Message-ID: <CANLsYkwfthuOQTCdgU2r6wXjYMeM1fGjvgr1TB1-TFpUXFBLOQ@mail.gmail.com>
Date: Wed, 12 Nov 2025 08:52:30 -0700
From: Mathieu Poirier <mathieu.poirier@...aro.org>
To: Dawei Li <dawei.li@...ux.dev>
Cc: andersson@...nel.org, linux-remoteproc@...r.kernel.org,
linux-kernel@...r.kernel.org, set_pte_at@...look.com,
Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [PATCH v2] rpmsg: char: Fix UAF and memory leak
On Wed, 12 Nov 2025 at 08:01, Dawei Li <dawei.li@...ux.dev> wrote:
>
> Potential UAF and memory leak exsit in exception handling paths for
> rpmsg_anonymous_eptdev_create(), fix them.
>
> While at it, rework the error handling of rpmsg_eptdev_add() and its
> callers, following rule of "release resource where it's allocated".
>
Please split this patch in two parts.
Thanks,
Mathieu
> Fixes: 2410558f5f11 ("rpmsg: char: Implement eptdev based on anonymous inode")
> Reported-by: Dan Carpenter <dan.carpenter@...aro.org>
> Closes: https://lore.kernel.org/all/aPi6gPZE2_ztOjIW@stanley.mountain/
>
> Signed-off-by: Dawei Li <dawei.li@...ux.dev>
> ---
> Change for v2:
> - Add put_device() when __rpmsg_eptdev_open() failed.
>
> Link to v1:
> https://lore.kernel.org/all/20251112142813.33708-1-dawei.li@linux.dev/
> ---
> drivers/rpmsg/rpmsg_char.c | 61 +++++++++++++++++++++-----------------
> 1 file changed, 34 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 34b35ea74aab..92c176e9b0e4 100644
> --- a/drivers/rpmsg/rpmsg_char.c
> +++ b/drivers/rpmsg/rpmsg_char.c
> @@ -460,44 +460,34 @@ static int rpmsg_eptdev_add(struct rpmsg_eptdev *eptdev,
>
> eptdev->chinfo = chinfo;
>
> - if (cdev) {
> - ret = ida_alloc_max(&rpmsg_minor_ida, RPMSG_DEV_MAX - 1, GFP_KERNEL);
> - if (ret < 0)
> - goto free_eptdev;
> -
> - dev->devt = MKDEV(MAJOR(rpmsg_major), ret);
> - }
> -
> /* Anonymous inode device still need device name for dev_err() and friends */
> ret = ida_alloc(&rpmsg_ept_ida, GFP_KERNEL);
> if (ret < 0)
> - goto free_minor_ida;
> + return ret;
> dev->id = ret;
> dev_set_name(dev, "rpmsg%d", ret);
>
> - ret = 0;
> -
> if (cdev) {
> + ret = ida_alloc_max(&rpmsg_minor_ida, RPMSG_DEV_MAX - 1, GFP_KERNEL);
> + if (ret < 0) {
> + ida_free(&rpmsg_ept_ida, dev->id);
> + return ret;
> + }
> +
> + dev->devt = MKDEV(MAJOR(rpmsg_major), ret);
> +
> ret = cdev_device_add(&eptdev->cdev, &eptdev->dev);
> - if (ret)
> - goto free_ept_ida;
> + if (ret) {
> + ida_free(&rpmsg_ept_ida, dev->id);
> + ida_free(&rpmsg_minor_ida, MINOR(dev->devt));
> + return ret;
> + }
> }
>
> /* We can now rely on the release function for cleanup */
> dev->release = rpmsg_eptdev_release_device;
>
> - return ret;
> -
> -free_ept_ida:
> - ida_free(&rpmsg_ept_ida, dev->id);
> -free_minor_ida:
> - if (cdev)
> - ida_free(&rpmsg_minor_ida, MINOR(dev->devt));
> -free_eptdev:
> - put_device(dev);
> - kfree(eptdev);
> -
> - return ret;
> + return 0;
> }
>
> static int rpmsg_chrdev_eptdev_add(struct rpmsg_eptdev *eptdev, struct rpmsg_channel_info chinfo)
> @@ -509,12 +499,17 @@ int rpmsg_chrdev_eptdev_create(struct rpmsg_device *rpdev, struct device *parent
> struct rpmsg_channel_info chinfo)
> {
> struct rpmsg_eptdev *eptdev;
> + int ret;
>
> eptdev = rpmsg_chrdev_eptdev_alloc(rpdev, parent);
> if (IS_ERR(eptdev))
> return PTR_ERR(eptdev);
>
> - return rpmsg_chrdev_eptdev_add(eptdev, chinfo);
> + ret = rpmsg_chrdev_eptdev_add(eptdev, chinfo);
> + if (ret)
> + kfree(eptdev);
> +
> + return ret;
> }
> EXPORT_SYMBOL(rpmsg_chrdev_eptdev_create);
>
> @@ -546,6 +541,11 @@ 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);
> + /*
> + * Avoid put_device() or WARN() will be triggered due to absence of
> + * device::release(), refer to device_release().
> + */
> + kfree(eptdev);
> return ret;
> }
>
> @@ -561,6 +561,8 @@ int rpmsg_anonymous_eptdev_create(struct rpmsg_device *rpdev, struct device *par
>
> if (!ret)
> *pfd = fd;
> + else
> + put_device(&eptdev->dev);
>
> return ret;
> }
> @@ -571,6 +573,7 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
> struct rpmsg_channel_info chinfo;
> struct rpmsg_eptdev *eptdev;
> struct device *dev = &rpdev->dev;
> + int ret;
>
> memcpy(chinfo.name, rpdev->id.name, RPMSG_NAME_SIZE);
> chinfo.src = rpdev->src;
> @@ -589,7 +592,11 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev)
> */
> eptdev->default_ept->priv = eptdev;
>
> - return rpmsg_chrdev_eptdev_add(eptdev, chinfo);
> + ret = rpmsg_chrdev_eptdev_add(eptdev, chinfo);
> + if (ret)
> + kfree(eptdev);
> +
> + return ret;
> }
>
> static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev)
> --
> 2.25.1
>
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