From: Alexander Potapenko <glider@google.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
Marco Elver <elver@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
kasan-dev <kasan-dev@googlegroups.com>,
LKML <linux-kernel@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Dave Hansen <dave.hansen@linux.intel.com>,
"H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [PATCH v2] x86: disable non-instrumented version of copy_mc when KMSAN is enabled
Date: Tue, 19 Mar 2024 13:38:45 +0100 [thread overview]
Message-ID: <CAG_fn=X71NCOnqNrtU9rJ4eeGZsxLCxKT=Cq9J9dq9q+Re9syA@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wgA1N72WfT9knweT=p1jhHGV3N0C2Z+7zvGL+LgG-AwXA@mail.gmail.com>
On Thu, Mar 7, 2024 at 1:09 AM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Wed, 6 Mar 2024 at 14:08, Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp> wrote:
> >
> > Something like below one?
>
> I'd rather leave the regular fallbacks (to memcpy and copy_to_user())
> alone, and I'd just put the
>
> kmsan_memmove(dst, src, len - ret);
>
> etc in the places that currently just call the MC copy functions.
(sorry for being late to the party)
We should probably use <linux/instrumented.h> here, as other tools
(KASAN and KCSAN) do not instrument copy_mc_to_kernel() either, and
might benefit from the same checks.
Something along the lines of:
================================
static __always_inline void
instrument_memcpy_before(const void *to, const void *from, unsigned long n)
{
kasan_check_write(to, n);
kasan_check_read(from, n);
kcsan_check_write(to, n);
kcsan_check_read(from, n);
}
static __always_inline void instrument_memcpy_after(const void *to,
const void *from,
unsigned long n,
unsigned long left)
{
kmsan_memcpy(to, n - left);
}
================================
(with kmsan_memcpy() working as Tetsuo described).
We can also update copy_mc_fragile_handle_tail() and copy_mc_to_user()
to call the instrumentation hooks.
Let me send the patches.
next prev parent reply other threads:[~2024-03-19 12:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-01 22:52 [PATCH v2] x86: disable non-instrumented version of copy_mc when KMSAN is enabled Tetsuo Handa
2024-03-05 11:31 ` Tetsuo Handa
2024-03-05 16:22 ` Thomas Gleixner
2024-03-05 17:57 ` Linus Torvalds
2024-03-06 22:08 ` Tetsuo Handa
2024-03-07 0:09 ` Linus Torvalds
2024-03-19 12:38 ` Alexander Potapenko [this message]
2024-03-06 9:16 ` Ingo Molnar
2024-03-06 10:12 ` Tetsuo Handa
2024-03-05 15:21 ` Dave Hansen
2024-03-05 16:50 ` Thomas Gleixner
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