linux-kernel - Re: [PATCH 3/5] net: renesas: rswitch: avoid use-after-put for a device tree node

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Message-ID: <bedaa242-b9ca-46a1-bc1c-433eb2d7c7ec@intel.com>
Date: Tue, 3 Dec 2024 16:24:26 -0800
From: Jacob Keller <jacob.e.keller@...el.com>
To: Nikita Yushchenko <nikita.yoush@...entembedded.com>, Yoshihiro Shimoda
	<yoshihiro.shimoda.uh@...esas.com>, Andrew Lunn <andrew@...n.ch>, "David S.
 Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, "Jakub
 Kicinski" <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, "Geert
 Uytterhoeven" <geert+renesas@...der.be>
CC: <netdev@...r.kernel.org>, <linux-renesas-soc@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Michael Dege <michael.dege@...esas.com>,
	Christian Mardmoeller <christian.mardmoeller@...esas.com>, Dennis Ostermann
	<dennis.ostermann@...esas.com>
Subject: Re: [PATCH 3/5] net: renesas: rswitch: avoid use-after-put for a
 device tree node



On 12/2/2024 5:49 AM, Nikita Yushchenko wrote:
> The device tree node saved in the rswitch_device structure is used at
> several driver locations. So passing this node to of_node_put() after
> the first use is wrong.
> 
> Move of_node_put() for this node to exit paths.
> 
> Fixes: b46f1e579329 ("net: renesas: rswitch: Simplify struct phy * handling")
> Signed-off-by: Nikita Yushchenko <nikita.yoush@...entembedded.com>
> ---

Reviewed-by: Jacob Keller <jacob.e.keller@...el.com>

>  drivers/net/ethernet/renesas/rswitch.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/renesas/rswitch.c b/drivers/net/ethernet/renesas/rswitch.c
> index 3ad5858d3cdd..779c05b8e05f 100644
> --- a/drivers/net/ethernet/renesas/rswitch.c
> +++ b/drivers/net/ethernet/renesas/rswitch.c
> @@ -1891,7 +1891,6 @@ static int rswitch_device_alloc(struct rswitch_private *priv, unsigned int index
>  	rdev->np_port = rswitch_get_port_node(rdev);
>  	rdev->disabled = !rdev->np_port;
>  	err = of_get_ethdev_address(rdev->np_port, ndev);
> -	of_node_put(rdev->np_port);
>  	if (err) {
>  		if (is_valid_ether_addr(rdev->etha->mac_addr))
>  			eth_hw_addr_set(ndev, rdev->etha->mac_addr);
> @@ -1921,6 +1920,7 @@ static int rswitch_device_alloc(struct rswitch_private *priv, unsigned int index
>  
>  out_rxdmac:
>  out_get_params:
> +	of_node_put(rdev->np_port);
>  	netif_napi_del(&rdev->napi);
>  	free_netdev(ndev);
>  
> @@ -1934,6 +1934,7 @@ static void rswitch_device_free(struct rswitch_private *priv, unsigned int index
>  
>  	rswitch_txdmac_free(ndev);
>  	rswitch_rxdmac_free(ndev);
> +	of_node_put(rdev->np_port);
>  	netif_napi_del(&rdev->napi);
>  	free_netdev(ndev);
>  }