netdev - Re: [PATCH v2] net: mdiobus: fix an OF node reference leak

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Message-ID: <f68d5c96-ac9f-4042-8f00-c6641d06eee4@lunn.ch>
Date: Sun, 15 Dec 2024 17:06:29 +0100
From: Andrew Lunn <andrew@...n.ch>
To: Joe Hattori <joe@...is.s.u-tokyo.ac.jp>
Cc: hkallweit1@...il.com, linux@...linux.org.uk, davem@...emloft.net,
	edumazet@...gle.com, kuba@...nel.org, pabeni@...hat.com,
	netdev@...r.kernel.org
Subject: Re: [PATCH v2] net: mdiobus: fix an OF node reference leak

On Sun, Dec 15, 2024 at 08:24:17PM +0900, Joe Hattori wrote:
> fwnode_find_mii_timestamper() calls of_parse_phandle_with_fixed_args()
> but does not decrement the refcount of the obtained OF node. Add an
> of_node_put() call before returning from the function.
> 
> This bug was detected by an experimental static analysis tool that I am
> developing.
> 
> Fixes: bc1bee3b87ee ("net: mdiobus: Introduce fwnode_mdiobus_register_phy()")
> Signed-off-by: Joe Hattori <joe@...is.s.u-tokyo.ac.jp>
> ---
> Changes in v2:
> - Call of_node_put() after calling register_mii_timestamper() to avoid
>   UAF.
> ---
>  drivers/net/mdio/fwnode_mdio.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/mdio/fwnode_mdio.c b/drivers/net/mdio/fwnode_mdio.c
> index b156493d7084..456f829e4d6d 100644
> --- a/drivers/net/mdio/fwnode_mdio.c
> +++ b/drivers/net/mdio/fwnode_mdio.c
> @@ -41,6 +41,7 @@ static struct mii_timestamper *
>  fwnode_find_mii_timestamper(struct fwnode_handle *fwnode)
>  {
>  	struct of_phandle_args arg;
> +	struct mii_timestamper *mii_ts;
>  	int err;
>  
>  	if (is_acpi_node(fwnode))
> @@ -56,7 +57,9 @@ fwnode_find_mii_timestamper(struct fwnode_handle *fwnode)
>  	if (arg.args_count != 1)
>  		return ERR_PTR(-EINVAL);

Is there no need to put the node when arg.args_count != 1 ?

	Andrew