Re: [PATCH v2] ipc/shm: fix the historical/wrong mm->start_stack check

[Oleg Nesterov]

On 08/26, Cyrill Gorcunov wrote:
>
> On Mon, Aug 25, 2014 at 09:12:07PM +0200, Oleg Nesterov wrote:
> > +		vma = find_vma(current->mm, addr);
> > +		if (vma) {
> > +			unsigned long end = addr + size;
> > +
> > +			if (vma->vm_flags & VM_GROWSDOWN)
> > +				end += PAGE_SIZE * 5;
> > +
> > +			if (end < addr || end > vma->vm_start)
> > +				goto invalid;
>
> Looks good to me, but I somehow missed in first version of the patch
> too the following aspect -- end > vma->vm_start? Maybe end >= vma->vm_end?

I think ">" is correct, the last byte is "addr + size - 1". Otherwise,
say, find_vma_intersection() is buggy. But this doesn't matter, please
see v3.

Oleg.

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