From: Peter Zijlstra <peterz@infradead.org>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrey Ryabinin <aryabinin@virtuozzo.com>,
Ingo Molnar <mingo@redhat.com>,
kasan-dev <kasan-dev@googlegroups.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86, kasan: add KASAN checks to atomic operations
Date: Mon, 6 Mar 2017 13:58:51 +0100 [thread overview]
Message-ID: <20170306125851.GL6500@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CACT4Y+YmpTMdJca-rE2nXR-qa=wn_bCqQXaRghtg1uC65-pKyA@mail.gmail.com>
On Mon, Mar 06, 2017 at 01:50:47PM +0100, Dmitry Vyukov wrote:
> On Mon, Mar 6, 2017 at 1:42 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> > KASAN uses compiler instrumentation to intercept all memory accesses.
> > But it does not see memory accesses done in assembly code.
> > One notable user of assembly code is atomic operations. Frequently,
> > for example, an atomic reference decrement is the last access to an
> > object and a good candidate for a racy use-after-free.
> >
> > Add manual KASAN checks to atomic operations.
> > Note: we need checks only before asm blocks and don't need them
> > in atomic functions composed of other atomic functions
> > (e.g. load-cmpxchg loops).
>
> Peter, also pointed me at arch/x86/include/asm/bitops.h. Will add them in v2.
>
> > static __always_inline void atomic_add(int i, atomic_t *v)
> > {
> > + kasan_check_write(v, sizeof(*v));
> > asm volatile(LOCK_PREFIX "addl %1,%0"
> > : "+m" (v->counter)
> > : "ir" (i));
So the problem is doing load/stores from asm bits, and GCC
(traditionally) doesn't try and interpret APP asm bits.
However, could we not write a GCC plugin that does exactly that?
Something that interprets the APP asm bits and generates these KASAN
bits that go with it?
next prev parent reply other threads:[~2017-03-06 13:24 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-06 12:42 [PATCH] x86, kasan: add KASAN checks to atomic operations Dmitry Vyukov
2017-03-06 12:50 ` Dmitry Vyukov
2017-03-06 12:58 ` Peter Zijlstra [this message]
2017-03-06 13:01 ` Peter Zijlstra
2017-03-06 14:24 ` Dmitry Vyukov
2017-03-06 15:20 ` Peter Zijlstra
2017-03-06 16:04 ` Mark Rutland
2017-03-06 15:33 ` Peter Zijlstra
2017-03-06 16:20 ` Mark Rutland
2017-03-06 16:27 ` Dmitry Vyukov
2017-03-06 17:25 ` Mark Rutland
2017-03-06 20:35 ` Peter Zijlstra
2017-03-08 13:42 ` Dmitry Vyukov
2017-03-08 15:20 ` Mark Rutland
2017-03-08 15:27 ` Dmitry Vyukov
2017-03-08 15:43 ` Mark Rutland
2017-03-08 15:45 ` Dmitry Vyukov
2017-03-08 15:48 ` Mark Rutland
2017-03-08 17:43 ` Will Deacon
2017-03-14 15:22 ` Dmitry Vyukov
2017-03-14 15:31 ` Peter Zijlstra
2017-03-14 15:32 ` Peter Zijlstra
2017-03-14 15:44 ` Mark Rutland
2017-03-14 19:25 ` Dmitry Vyukov
2017-03-06 16:48 ` Andrey Ryabinin
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