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[PATCH v1] irqchip: irq-mips-gic:- Handle return NULL error from ioremap_nocache

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  [PATCH v1] irqchip: irq-mips-gic:- Handle return NULL error from ioremap_nocache Arvind Yadav <arvind.yadav.cs@gmail.com> - 2017-01-09 09:10 +0100
    Re: [PATCH v1] irqchip: irq-mips-gic:- Handle return NULL error from  ioremap_nocache Marc Zyngier <marc.zyngier@arm.com> - 2017-01-09 10:10 +0100

#1554135 — [PATCH v1] irqchip: irq-mips-gic:- Handle return NULL error from ioremap_nocache

Here, If ioremap_nocache will fail. It will return NULL.
Kernel can run into a NULL-pointer dereference.
This error check will avoid NULL pointer dereference.

Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
---
 drivers/irqchip/irq-mips-gic.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
index c01c09e..eeea2e8 100644
--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c
@@ -979,6 +979,8 @@ 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)
+		panic("Failed to map GIC memory");
 
 	gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG));
 	gic_shared_intrs = (gicconfig & GIC_SH_CONFIG_NUMINTRS_MSK) >>
-- 
1.9.1

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#1554162 — Re: [PATCH v1] irqchip: irq-mips-gic:- Handle return NULL error from ioremap_nocache

On 09/01/17 08:08, Arvind Yadav wrote:
> Here, If ioremap_nocache will fail. It will return NULL.
> Kernel can run into a NULL-pointer dereference.
> This error check will avoid NULL pointer dereference.
> 
> Signed-off-by: Arvind Yadav <arvind.yadav.cs@gmail.com>
> ---
>  drivers/irqchip/irq-mips-gic.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-mips-gic.c b/drivers/irqchip/irq-mips-gic.c
> index c01c09e..eeea2e8 100644
> --- a/drivers/irqchip/irq-mips-gic.c
> +++ b/drivers/irqchip/irq-mips-gic.c
> @@ -979,6 +979,8 @@ 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)
> +		panic("Failed to map GIC memory");

So you're replacing a panic due to dereferencing a NULL pointer with
another panic -- not much progress here. I appreciate that the message
is a bit more explicit, but is there something slightly less drastic we
could do? Like returning an error code and see if the kernel otherwise
recovers (possibly with reduced functionality)?

>  
>  	gicconfig = gic_read(GIC_REG(SHARED, GIC_SH_CONFIG));
>  	gic_shared_intrs = (gicconfig & GIC_SH_CONFIG_NUMINTRS_MSK) >>
> 

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...

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