netdev - Re: [PATCH v2] net: mdio: fix unbalanced fwnode reference count in mdio_device

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

Message-ID: <a1df3cb4676ce4f51680b9ead3dcf01d561eed99.camel@redhat.com>
Date:   Tue, 06 Dec 2022 12:34:55 +0100
From:   Paolo Abeni <pabeni@...hat.com>
To:     Zeng Heng <zengheng4@...wei.com>, hkallweit1@...il.com,
        edumazet@...gle.com, kuba@...nel.org, davem@...emloft.net,
        andrew@...n.ch, f.fainelli@...il.com, linux@...linux.org.uk
Cc:     liwei391@...wei.com, netdev@...r.kernel.org
Subject: Re: [PATCH v2] net: mdio: fix unbalanced fwnode reference count in
 mdio_device_release()

Hello,
On Sat, 2022-12-03 at 15:34 +0800, Zeng Heng wrote:
> There is warning report about of_node refcount leak
> while probing mdio device:
> 
> OF: ERROR: memory leak, expected refcount 1 instead of 2,
> of_node_get()/of_node_put() unbalanced - destroy cset entry:
> attach overlay node /spi/soc@...dio@...700c0/ethernet@4
> 
> In of_mdiobus_register_device(), we increase fwnode refcount
> by fwnode_handle_get() before associating the of_node with
> mdio device, but it has never been decreased in normal path.
> Since that, in mdio_device_release(), it needs to call
> fwnode_handle_put() in addition instead of calling kfree()
> directly.
> 
> After above, just calling mdio_device_free() in the error handle
> path of of_mdiobus_register_device() is enough to keep the
> refcount balanced.
> 
> Fixes: a9049e0c513c ("mdio: Add support for mdio drivers.")
> Signed-off-by: Zeng Heng <zengheng4@...wei.com>
> Reviewed-by: Yang Yingliang <yangyingliang@...wei.com>
> ---
>  changes in v2:
>   - Add operation about setting device node as NULL-pointer.
>     There is no practical changes.
>   - Add reviewed-by tag.
> ---
>  drivers/net/mdio/of_mdio.c    | 3 ++-
>  drivers/net/phy/mdio_device.c | 2 ++
>  2 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/mdio/of_mdio.c b/drivers/net/mdio/of_mdio.c
> index 796e9c7857d0..510822d6d0d9 100644
> --- a/drivers/net/mdio/of_mdio.c
> +++ b/drivers/net/mdio/of_mdio.c
> @@ -68,8 +68,9 @@ static int of_mdiobus_register_device(struct mii_bus *mdio,
>  	/* All data is now stored in the mdiodev struct; register it. */
>  	rc = mdio_device_register(mdiodev);
>  	if (rc) {
> +		device_set_node(&mdiodev->dev, NULL);
> +		fwnode_handle_put(fwnode);
>  		mdio_device_free(mdiodev);
> -		of_node_put(child);
>  		return rc;
>  	}
>  
> diff --git a/drivers/net/phy/mdio_device.c b/drivers/net/phy/mdio_device.c
> index 250742ffdfd9..044828d081d2 100644
> --- a/drivers/net/phy/mdio_device.c
> +++ b/drivers/net/phy/mdio_device.c
> @@ -21,6 +21,7 @@
>  #include <linux/slab.h>
>  #include <linux/string.h>
>  #include <linux/unistd.h>
> +#include <linux/property.h>
>  
>  void mdio_device_free(struct mdio_device *mdiodev)
>  {
> @@ -30,6 +31,7 @@ EXPORT_SYMBOL(mdio_device_free);
>  
>  static void mdio_device_release(struct device *dev)
>  {
> +	fwnode_handle_put(dev->fwnode);
>  	kfree(to_mdio_device(dev));
>  }
> 
The patch LGTM, but I'll wait a bit more just in case Andrew want to
comment on it.

Cheers,

Paolo