Re: fix a hyperv W^X violation and remove vmalloc_exec

[Peter Zijlstra]

On Thu, Jun 18, 2020 at 08:43:04AM +0200, Christoph Hellwig wrote:
> Hi all,
> 
> Dexuan reported a W^X violation due to the fact that the hyper hypercall
> page due switching it to be allocated using vmalloc_exec.  The problem
> is that PAGE_KERNEL_EXEC as used by vmalloc_exec actually sets writable
> permissions in the pte.  This series fixes the issue by switching to the
> low-level __vmalloc_node_range interface that allows specifing more
> detailed permissions instead.  It then also open codes the other two
> callers and removes the somewhat confusing vmalloc_exec interface.

Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

> Peter noted that the hyper hypercall page allocation also has another
> long standing issue in that it shouldn't use the full vmalloc but just
> the module space.  This issue is so far theoretical as the allocation is
> done early in the boot process.  I plan to fix it with another bigger
> series for 5.9.

Thanks!