Re: [PATCH 5/5] arm64/vdso: Restrict splitting VVAR VMA

[Vincenzo Frascino]

Hi Andrei,

On 2/23/20 11:30 PM, Andrei Vagin wrote:
[...]

> 
> Hmmm. I have read the code of special_mapping_mremap() and I don't see where
> it restricts splitting the vvar mapping.
> 
> Here is the code what I see in the source:
> 
> static int special_mapping_mremap(struct vm_area_struct *new_vma)
> {
>         struct vm_special_mapping *sm = new_vma->vm_private_data;
> 
>         if (WARN_ON_ONCE(current->mm != new_vma->vm_mm))
>                 return -EFAULT;
> 
>         if (sm->mremap)
>                 return sm->mremap(sm, new_vma);
> 
>         return 0;
> }
> 
> And I have checked that without this patch, I can remap only one page of
> the vvar mapping.
>

I checked it a second time and I agree. The check on new_size is required in
this case.

> Thanks,
> Andrei
> 

-- 
Regards,
Vincenzo