Re: [PATCH] arm64: fix wrong check of on_sdei_stack in nmi context

[Julien Thierry <julien.thierry@arm.com>]

Hi Wei,

On 01/04/2019 04:55, Wei Li wrote:
> When doing unwind_frame() in the context of pseudo nmi (need enable
> CONFIG_ARM64_PSEUDO_NMI), reaching the botton of the stack (fp == 0,
> pc != 0), function on_sdei_stack() will return true while the sdei acpi
> table is not inited in fact. This will cause a "NULL pointer dereference"
> oops when going on.
> 
> Signed-off-by: Wei Li <liwei391@huawei.com>

Thanks for catching this. The change makes sense to me.

Reviewed-by: Julien Thierry <julien.thierry@arm.com>

> ---
>  arch/arm64/kernel/sdei.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm64/kernel/sdei.c b/arch/arm64/kernel/sdei.c
> index 5ba4465e44f0..ea94cf8f9dc6 100644
> --- a/arch/arm64/kernel/sdei.c
> +++ b/arch/arm64/kernel/sdei.c
> @@ -94,6 +94,9 @@ static bool on_sdei_normal_stack(unsigned long sp, struct stack_info *info)
>  	unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_normal_ptr);
>  	unsigned long high = low + SDEI_STACK_SIZE;
>  
> +	if (!low)
> +		return false;
> +
>  	if (sp < low || sp >= high)
>  		return false;
>  
> @@ -111,6 +114,9 @@ static bool on_sdei_critical_stack(unsigned long sp, struct stack_info *info)
>  	unsigned long low = (unsigned long)raw_cpu_read(sdei_stack_critical_ptr);
>  	unsigned long high = low + SDEI_STACK_SIZE;
>  
> +	if (!low)
> +		return false;
> +
>  	if (sp < low || sp >= high)
>  		return false;
>  
> 

-- 
Julien Thierry

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