Date: Thu, 10 Nov 2016 22:39:52 +0100 From: Peter Zijlstra <peterz@...radead.org> To: David Windsor <dave@...gbits.org> Cc: kernel-hardening@...ts.openwall.com, Will Deacon <will.deacon@....com>, Greg KH <gregkh@...uxfoundation.org>, Elena Reshetova <elena.reshetova@...el.com>, Arnd Bergmann <arnd@...db.de>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, "H. Peter Anvin" <h.peter.anvin@...el.com>, LKML <linux-kernel@...r.kernel.org> Subject: Re: Re: [RFC v4 PATCH 00/13] HARDENED_ATOMIC On Thu, Nov 10, 2016 at 04:23:08PM -0500, David Windsor wrote: > Discussions have been occurring since KSPP has begun: do we need a Note that I was not included in any of that. If you hide in a corner on the intartubes don't be surprised people have no clue what you're on about. > specialized type for reference counters? Oh, wait, we do: kref. > Wait! kref is implemented with atomic_t. > > So, what? We obviously need an atomicity for a reference counter > type. So, do we simply implement the HARDENED_ATOMIC protected > version of atomic_t "inside" of kref and leave atomic_t alone? But you could provide a small subset of the atomic_t API for that, under a different type. That way you don't get utter shite like atomic_cmpxchg_wrap() for instance. >From what I can see only all the add/sub variants have overflow checks, but all the operations get _wrap() prefixes, even where it doesn't make any bloody sense. _wrap() on bitops?, _wrap() on cmpxchg(). You must be bloody joking right?
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