From: Thomas Gleixner <tglx@linutronix.de>
To: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
linuxram@us.ibm.com, dave.hansen@intel.com, mpe@ellerman.id.au,
mingo@kernel.org, akpm@linux-foundation.org, shuah@kernel.org
Subject: Re: [PATCH 1/3] x86, pkeys: do not special case protection key 0
Date: Sat, 17 Mar 2018 10:12:15 +0100 (CET) [thread overview]
Message-ID: <alpine.DEB.2.21.1803171011100.1509@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20180316214656.0E059008@viggo.jf.intel.com>
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
next prev parent reply other threads:[~2018-03-17 9:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-16 21:46 [PATCH 0/3] x86, pkeys: make pkey 0 more normal Dave Hansen
2018-03-16 21:46 ` [PATCH 1/3] x86, pkeys: do not special case protection key 0 Dave Hansen
2018-03-17 9:12 ` Thomas Gleixner [this message]
2018-03-17 16:01 ` Dave Hansen
2018-03-17 19:05 ` Thomas Gleixner
2018-03-19 5:50 ` Michael Ellerman
2018-03-17 23:24 ` Ram Pai
2018-03-18 0:49 ` Dave Hansen
2018-03-18 9:30 ` Thomas Gleixner
2018-03-18 23:46 ` Ram Pai
2018-03-16 21:46 ` [PATCH 2/3] x86, pkeys, selftests: save off 'prot' for allocations Dave Hansen
2018-03-16 21:46 ` [PATCH 3/3] x86, pkeys, selftests: add a test for pkey 0 Dave Hansen
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