Re: [PATCH] phy: ti: am654-serdes: fix an use-after-free in serdes_am654_clk_register()

[Roger Quadros]

On 08/07/2019 09:19, Wen Yang wrote:
> The regmap_node variable is still being used in the syscon_node_to_regmap()
> call after the of_node_put() call, which may result in use-after-free.
> 
> Fixes: 71e2f5c5c224 ("phy: ti: Add a new SERDES driver for TI's AM654x SoC")
> Signed-off-by: Wen Yang <wen.yang99@xxxxxxxxxx>
> Cc: Kishon Vijay Abraham I <kishon@xxxxxx>
> Cc: Roger Quadros <rogerq@xxxxxx>
> Cc: linux-kernel@xxxxxxxxxxxxxxx

Reviewed-by: Roger Quadros <rogerq@xxxxxx>

> ---
>  drivers/phy/ti/phy-am654-serdes.c | 33 ++++++++++++++++++++++-----------
>  1 file changed, 22 insertions(+), 11 deletions(-)
> 
> diff --git a/drivers/phy/ti/phy-am654-serdes.c b/drivers/phy/ti/phy-am654-serdes.c
> index f8edd08..f14f1f0 100644
> --- a/drivers/phy/ti/phy-am654-serdes.c
> +++ b/drivers/phy/ti/phy-am654-serdes.c
> @@ -405,6 +405,7 @@ static int serdes_am654_clk_register(struct serdes_am654 *am654_phy,
>  	const __be32 *addr;
>  	unsigned int reg;
>  	struct clk *clk;
> +	int ret = 0;
>  
>  	mux = devm_kzalloc(dev, sizeof(*mux), GFP_KERNEL);
>  	if (!mux)
> @@ -413,34 +414,40 @@ static int serdes_am654_clk_register(struct serdes_am654 *am654_phy,
>  	init = &mux->clk_data;
>  
>  	regmap_node = of_parse_phandle(node, "ti,serdes-clk", 0);
> -	of_node_put(regmap_node);
>  	if (!regmap_node) {
>  		dev_err(dev, "Fail to get serdes-clk node\n");
> -		return -ENODEV;
> +		ret = -ENODEV;
> +		goto out_put_node;
>  	}
>  
>  	regmap = syscon_node_to_regmap(regmap_node->parent);
>  	if (IS_ERR(regmap)) {
>  		dev_err(dev, "Fail to get Syscon regmap\n");
> -		return PTR_ERR(regmap);
> +		ret = PTR_ERR(regmap);
> +		goto out_put_node;
>  	}
>  
>  	num_parents = of_clk_get_parent_count(node);
>  	if (num_parents < 2) {
>  		dev_err(dev, "SERDES clock must have parents\n");
> -		return -EINVAL;
> +		ret = -EINVAL;
> +		goto out_put_node;
>  	}
>  
>  	parent_names = devm_kzalloc(dev, (sizeof(char *) * num_parents),
>  				    GFP_KERNEL);
> -	if (!parent_names)
> -		return -ENOMEM;
> +	if (!parent_names) {
> +		ret = -ENOMEM;
> +		goto out_put_node;
> +	}
>  
>  	of_clk_parent_fill(node, parent_names, num_parents);
>  
>  	addr = of_get_address(regmap_node, 0, NULL, NULL);
> -	if (!addr)
> -		return -EINVAL;
> +	if (!addr) {
> +		ret = -EINVAL;
> +		goto out_put_node;
> +	}
>  
>  	reg = be32_to_cpu(*addr);
>  
> @@ -456,12 +463,16 @@ static int serdes_am654_clk_register(struct serdes_am654 *am654_phy,
>  	mux->hw.init = init;
>  
>  	clk = devm_clk_register(dev, &mux->hw);
> -	if (IS_ERR(clk))
> -		return PTR_ERR(clk);
> +	if (IS_ERR(clk)) {
> +		ret = PTR_ERR(clk);
> +		goto out_put_node;
> +	}
>  
>  	am654_phy->clks[clock_num] = clk;
>  
> -	return 0;
> +out_put_node:
> +	of_node_put(regmap_node);
> +	return ret;
>  }
>  
>  static const struct of_device_id serdes_am654_id_table[] = {
> 

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