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

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Date:	Mon, 19 May 2014 02:49:26 +0000
From:	"Li.Xiubo@...escale.com" <Li.Xiubo@...escale.com>
To:	Nicolas Pitre <nicolas.pitre@...aro.org>
CC:	"linux@....linux.org.uk" <linux@....linux.org.uk>,
	"lauraa@...eaurora.org" <lauraa@...eaurora.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"santosh.shilimkar@...com" <santosh.shilimkar@...com>,
	"iamjoonsoo.kim@....com" <iamjoonsoo.kim@....com>,
	"superlibj8301@...il.com" <superlibj8301@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3] arm: ioremap: Fix static vm area boundary check.

> > 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.
> 

Yes, you are right, I'm thinking why the static area has no guard page?

Thanks very much,

BRs
Xiubo


> 
> > 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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