linux-kernel - Re: [PATCH] rpmsg: char: Fix UAF and memory leak

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <mxctlnzpywrdahcvuahmxaa4h5vttz6p5yiu7jvtsemahjcsgj@bflvnu7viwff>
Date: Wed, 12 Nov 2025 10:42:01 -0600
From: Bjorn Andersson <andersson@...nel.org>
To: Dawei Li <dawei.li@...ux.dev>
Cc: mathieu.poirier@...aro.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] rpmsg: char: Fix UAF and memory leak

On Wed, Nov 12, 2025 at 10:28:13PM +0800, Dawei Li wrote:
> Potential UAF and memory leak exsit in exception handling paths for
> rpmsg_anonymous_eptdev_create(), fix them.

Please describe the condition where this happens.

> 
> While at it, rework the error handling of rpmsg_eptdev_add() and its
> callers, following rule of "release resource where it's allocated".

Can this be done in a separate patch, to limit the impact of the two
parts of this change?

Regards,
Bjorn

> 
> 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>
> ---
>  drivers/rpmsg/rpmsg_char.c | 59 +++++++++++++++++++++-----------------
>  1 file changed, 32 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c
> index 34b35ea74aab..de058a8b99ff 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;
>  	}
>  
> @@ -571,6 +571,7 @@ 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 +590,11 @@ 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
>