linux-kernel - Re: [PATCH v3] arm: ioremap: Fix static vm area boundary check.

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Date:	Fri, 16 May 2014 14:11:25 -0400 (EDT)
From:	Nicolas Pitre <nicolas.pitre@...aro.org>
To:	Xiubo Li <Li.Xiubo@...escale.com>
cc:	linux@....linux.org.uk, lauraa@...eaurora.org,
	linux-arm-kernel@...ts.infradead.org, santosh.shilimkar@...com,
	iamjoonsoo.kim@....com, superlibj8301@...il.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] arm: ioremap: Fix static vm area boundary check.

On Fri, 16 May 2014, Xiubo Li wrote:

> For each vmalloc area, there is one guard page at the end of it.
> so the vm->size = PAGE_ALIGN(offset + request size) + guard page size.

Nope.  There is no guard page for statically created vmalloc areas.


> Signed-off-by: Richard Lee <superlibj8301@...il.com>
> Signed-off-by: Xiubo Li <Li.Xiubo@...escale.com>
> Cc: Nicolas Pitre <nico@...aro.org>
> Cc: Santosh Shilimkar <santosh.shilimkar@...com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@....com>
> ---
>  arch/arm/mm/ioremap.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
> index be69333..758e8f7 100644
> --- a/arch/arm/mm/ioremap.c
> +++ b/arch/arm/mm/ioremap.c
> @@ -49,14 +49,18 @@ static struct static_vm *find_static_vm_paddr(phys_addr_t paddr,
>  	struct vm_struct *vm;
>  
>  	list_for_each_entry(svm, &static_vmlist, list) {
> +		phys_addr_t paddr_end, phys_addr_end;
> +
>  		vm = &svm->vm;
>  		if (!(vm->flags & VM_ARM_STATIC_MAPPING))
>  			continue;
>  		if ((vm->flags & VM_ARM_MTYPE_MASK) != VM_ARM_MTYPE(mtype))
>  			continue;
>  
> -		if (vm->phys_addr > paddr ||
> -			paddr + size - 1 > vm->phys_addr + vm->size - 1)
> +		/* The PAGE_SIZE here is vmalloc area's guard page */
> +		phys_addr_end = vm->phys_addr + vm->size - PAGE_SIZE - 1;
> +		paddr_end = paddr + size - 1;
> +		if (vm->phys_addr > paddr || paddr_end > phys_addr_end)
>  			continue;
>  
>  		return svm;
> -- 
> 1.8.4
> 
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