[PATCH kernel v2 1/6] KVM: PPC: Rework H_PUT_TCE/H_GET_TCE handlers

[Paul Mackerras]

On Fri, Jan 22, 2016 at 12:59:47PM +1100, Alexey Kardashevskiy wrote:
> On 01/22/2016 11:42 AM, David Gibson wrote:
> >On Thu, Jan 21, 2016 at 06:39:32PM +1100, Alexey Kardashevskiy wrote:
[snip]
> >>+	if ((ioba & mask) || (idx + npages > size))
> >
> >It doesn't matter for the current callers, but you should check for
> >overflow in idx + npages as well.
> 
> 
> npages can be only 1..512 and this is checked in H_PUT_TCE/etc handlers.
> idx is 52bit long max.
> And this is not going to change because H_PUT_TCE_INDIRECT will always be
> limited by 512 (or one 4K page).
> 
> Do I still need the overflow check here?

You could add "|| npages > TCES_PER_PAGE" and that would make it clear
that there can't be any overflow, and it should get removed by the
compiler for the calls with constant npages.

Paul.