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SubjectRe: [PATCH 1/3] x86, pkeys: do not special case protection key 0
On Fri, 16 Mar 2018, Dave Hansen wrote:

>
> From: Dave Hansen <dave.hansen@linux.intel.com>
>
> mm_pkey_is_allocated() treats pkey 0 as unallocated. That is
> inconsistent with the manpages, and also inconsistent with
> mm->context.pkey_allocation_map. Stop special casing it and only
> disallow values that are actually bad (< 0).
>
> The end-user visible effect of this is that you can now use
> mprotect_pkey() to set pkey=0.
>
> This is a bit nicer than what Ram proposed because it is simpler
> and removes special-casing for pkey 0. On the other hand, it does
> allow applciations to pkey_free() pkey-0, but that's just a silly
> thing to do, so we are not going to protect against it.

What's the consequence of that? Application crashing and burning itself or
something more subtle?

Thanks,

tglx

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