linux-kernel - Re: [PATCH] irqchip/stm32: fix init error handling

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Date:   Wed, 8 Aug 2018 14:29:29 +0200
From:   Ludovic BARRE <ludovic.barre@...com>
To:     Dan Carpenter <dan.carpenter@...cle.com>,
        Thomas Gleixner <tglx@...utronix.de>
CC:     Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Alexandre Torgue <alexandre.torgue@...com>,
        <linux-kernel@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH] irqchip/stm32: fix init error handling

oh yes, host_data is dereferenced (for kfree into out_free_mem) if 
stm32_exti_host_init fail

thanks Dan

BR
Ludo

On 08/08/2018 02:03 PM, Dan Carpenter wrote:
> If there are any errors in stm32_exti_host_init() then it leads to a
> NULL dereference in the callers.  The function should clean up after
> itself.
> 
> Fixes: f9fc1745501e ("irqchip/stm32: Add host and driver data structures")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>

Reviewed-by: Ludovic Barre <ludovic.barre@...com>

> 
> diff --git a/drivers/irqchip/irq-stm32-exti.c b/drivers/irqchip/irq-stm32-exti.c
> index 3df527fcf4e1..0a2088e12d96 100644
> --- a/drivers/irqchip/irq-stm32-exti.c
> +++ b/drivers/irqchip/irq-stm32-exti.c
> @@ -603,17 +603,24 @@ stm32_exti_host_data *stm32_exti_host_init(const struct stm32_exti_drv_data *dd,
>   					sizeof(struct stm32_exti_chip_data),
>   					GFP_KERNEL);
>   	if (!host_data->chips_data)
> -		return NULL;
> +		goto free_host_data;
>   
>   	host_data->base = of_iomap(node, 0);
>   	if (!host_data->base) {
>   		pr_err("%pOF: Unable to map registers\n", node);
> -		return NULL;
> +		goto free_chips_data;
>   	}
>   
>   	stm32_host_data = host_data;
>   
>   	return host_data;
> +
> +free_chips_data:
> +	kfree(host_data->chips_data);
> +free_host_data:
> +	kfree(host_data);
> +
> +	return NULL;
>   }
>   
>   static struct
> @@ -665,10 +672,8 @@ static int __init stm32_exti_init(const struct stm32_exti_drv_data *drv_data,
>   	struct irq_domain *domain;
>   
>   	host_data = stm32_exti_host_init(drv_data, node);
> -	if (!host_data) {
> -		ret = -ENOMEM;
> -		goto out_free_mem;
> -	}
> +	if (!host_data)
> +		return -ENOMEM;
>   
>   	domain = irq_domain_add_linear(node, drv_data->bank_nr * IRQS_PER_BANK,
>   				       &irq_exti_domain_ops, NULL);
> @@ -725,7 +730,6 @@ static int __init stm32_exti_init(const struct stm32_exti_drv_data *drv_data,
>   	irq_domain_remove(domain);
>   out_unmap:
>   	iounmap(host_data->base);
> -out_free_mem:
>   	kfree(host_data->chips_data);
>   	kfree(host_data);
>   	return ret;
> @@ -752,10 +756,8 @@ __init stm32_exti_hierarchy_init(const struct stm32_exti_drv_data *drv_data,
>   	}
>   
>   	host_data = stm32_exti_host_init(drv_data, node);
> -	if (!host_data) {
> -		ret = -ENOMEM;
> -		goto out_free_mem;
> -	}
> +	if (!host_data)
> +		return -ENOMEM;
>   
>   	for (i = 0; i < drv_data->bank_nr; i++)
>   		stm32_exti_chip_init(host_data, i, node);
> @@ -777,7 +779,6 @@ __init stm32_exti_hierarchy_init(const struct stm32_exti_drv_data *drv_data,
>   
>   out_unmap:
>   	iounmap(host_data->base);
> -out_free_mem:
>   	kfree(host_data->chips_data);
>   	kfree(host_data);
>   	return ret;
>