linux-kernel - Re: [PATCH v2] irqchip: irq-mips-gic:- Avoiding Kernel panics due to Error.

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Date:   Tue, 17 Jan 2017 09:38:03 +0100 (CET)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Arvind Yadav <arvind.yadav.cs@...il.com>
cc:     Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <marc.zyngier@....com>,
        LKML <linux-kernel@...r.kernel.org>,
        Paul Burton <paul.burton@...tec.com>, linux-mips@...ux-mips.org
Subject: Re: [PATCH v2] irqchip: irq-mips-gic:- Avoiding Kernel panics due
 to Error.

On Mon, 16 Jan 2017, Arvind Yadav wrote:

Cc'ing the MIPS folks.

> Eliminating kernel panic due to NULL pointer dereferencing and
> other failure in __gic_init.
> Here, __gic_init can fail. This error check will avoid NULL pointer
> dereference and kernel panic.
> 
> Signed-off-by: Arvind Yadav <arvind.yadav.cs@...il.com>
> ---
>  drivers/irqchip/irq-mips-gic.c | 40 +++++++++++++++++++++++++++++++---------
>  1 file changed, 31 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
> index c01c09e..bf0816f 100644
> --- a/drivers/irqchip/irq-mips-gic.c
> +++ b/drivers/irqchip/irq-mips-gic.c
> @@ -968,7 +968,7 @@ int gic_ipi_domain_match(struct irq_domain *d, struct device_node *node,
>  	.match = gic_ipi_domain_match,
>  };
>  
> -static void __init __gic_init(unsigned long gic_base_addr,
> +static int  __init __gic_init(unsigned long gic_base_addr,
>  			      unsigned long gic_addrspace_size,
>  			      unsigned int cpu_vec, unsigned int irqbase,
>  			      struct device_node *node)
> @@ -979,6 +979,10 @@ static void __init __gic_init(unsigned long gic_base_addr,
>  	__gic_base_addr = gic_base_addr;
>  
>  	gic_base = ioremap_nocache(gic_base_addr, gic_addrspace_size);
> +	if (!gic_base) {
> +		pr_err("Failed to map GIC memory");
> +		return -ENOMEM;
> +	}
>  
>  	gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG));
>  	gic_shared_intrs = (gicconfig & GIC_SH_CONFIG_NUMINTRS_MSK) >>
> @@ -1035,23 +1039,29 @@ static void __init __gic_init(unsigned long gic_base_addr,
>  	gic_irq_domain = irq_domain_add_simple(node, GIC_NUM_LOCAL_INTRS +
>  					       gic_shared_intrs, irqbase,
>  					       &gic_irq_domain_ops, NULL);
> -	if (!gic_irq_domain)
> -		panic("Failed to add GIC IRQ domain");
> +	if (!gic_irq_domain) {
> +		pr_err("Failed to add GIC IRQ domain");
> +		goto iounmap;
> +	}
>  	gic_irq_domain->name = "mips-gic-irq";
>  
>  	gic_dev_domain = irq_domain_add_hierarchy(gic_irq_domain, 0,
>  						  GIC_NUM_LOCAL_INTRS + gic_shared_intrs,
>  						  node, &gic_dev_domain_ops, NULL);
> -	if (!gic_dev_domain)
> -		panic("Failed to add GIC DEV domain");
> +	if (!gic_dev_domain) {
> +		pr_err("Failed to add GIC DEV domain");
> +		goto iounmap;
> +	}
>  	gic_dev_domain->name = "mips-gic-dev";
>  
>  	gic_ipi_domain = irq_domain_add_hierarchy(gic_irq_domain,
>  						  IRQ_DOMAIN_FLAG_IPI_PER_CPU,
>  						  GIC_NUM_LOCAL_INTRS + gic_shared_intrs,
>  						  node, &gic_ipi_domain_ops, NULL);
> -	if (!gic_ipi_domain)
> -		panic("Failed to add GIC IPI domain");
> +	if (!gic_ipi_domain) {
> +		pr_err("Failed to add GIC IPI domain");
> +		goto iounmap;
> +	}
>  
>  	gic_ipi_domain->name = "mips-gic-ipi";
>  	gic_ipi_domain->bus_token = DOMAIN_BUS_IPI;
> @@ -1067,13 +1077,22 @@ static void __init __gic_init(unsigned long gic_base_addr,
>  	}
>  
>  	gic_basic_init();
> +	return 0;
> +iounmap:
> +	iounmap(gic_base);
> +	return -ENOMEM;
>  }
>  
>  void __init gic_init(unsigned long gic_base_addr,
>  		     unsigned long gic_addrspace_size,
>  		     unsigned int cpu_vec, unsigned int irqbase)
>  {
> -	__gic_init(gic_base_addr, gic_addrspace_size, cpu_vec, irqbase, NULL);
> +	int ret;
> +
> +	ret = __gic_init(gic_base_addr, gic_addrspace_size, cpu_vec, irqbase,
> +			 NULL);
> +	if (ret)
> +		pr_err("Failed to initialize GIC");
>  }
>  
>  static int __init gic_of_init(struct device_node *node,
> @@ -1083,6 +1102,7 @@ static int __init gic_of_init(struct device_node *node,
>  	unsigned int cpu_vec, i = 0, reserved = 0;
>  	phys_addr_t gic_base;
>  	size_t gic_len;
> +	int ret;
>  
>  	/* Find the first available CPU vector. */
>  	while (!of_property_read_u32_index(node, "mti,reserved-cpu-vectors",
> @@ -1119,7 +1139,9 @@ static int __init gic_of_init(struct device_node *node,
>  		write_gcr_gic_base(gic_base | CM_GCR_GIC_BASE_GICEN_MSK);
>  	gic_present = true;
>  
> -	__gic_init(gic_base, gic_len, cpu_vec, 0, node);
> +	ret = __gic_init(gic_base, gic_len, cpu_vec, 0, node);
> +	if (ret)
> +		return ret;
>  
>  	return 0;
>  }
> -- 
> 1.9.1
> 
>