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From: Mark Rutland <mark.rutland@arm.com>
To: Marco Elver <elver@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Alexander Potapenko <glider@google.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"Paul E. McKenney" <paulmck@kernel.org>,
	Andrey Konovalov <andreyknvl@google.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Christoph Lameter <cl@linux.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	David Rientjes <rientjes@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Eric Dumazet <edumazet@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Hillf Danton <hdanton@sina.com>, Ingo Molnar <mingo@redhat.com>,
	Jann Horn <jannh@google.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Kees Cook <keescook@chromium.org>,
	Pekka Enberg <penberg@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	SeongJae Park <sjpark@amazon.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Vlastimil Babka <vbabka@suse.cz>, Will Deacon <will@kernel.org>,
	the arch/x86 maintainers <x86@kernel.org>,
	"open list:DOCUMENTATION" <linux-doc@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	kasan-dev <kasan-dev@googlegroups.com>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Linux Memory Management List <linux-mm@kvack.org>
Subject: Re: [PATCH v3 01/10] mm: add Kernel Electric-Fence infrastructure
Date: Tue, 29 Sep 2020 16:05:49 +0100	[thread overview]
Message-ID: <20200929150549.GE53442@C02TD0UTHF1T.local> (raw)
In-Reply-To: <CANpmjNNQGrpq+fBh4OypP9aK+-548vbCbKYiWQnSHESM0SLVzw@mail.gmail.com>

On Tue, Sep 29, 2020 at 04:51:29PM +0200, Marco Elver wrote:
> On Tue, 29 Sep 2020 at 16:24, Mark Rutland <mark.rutland@arm.com> wrote:
> [...]
> >
> > From other sub-threads it sounds like these addresses are not part of
> > the linear/direct map. Having kmalloc return addresses outside of the
> > linear map is going to break anything that relies on virt<->phys
> > conversions, and is liable to make DMA corrupt memory. There were
> > problems of that sort with VMAP_STACK, and this is why kvmalloc() is
> > separate from kmalloc().
> >
> > Have you tested with CONFIG_DEBUG_VIRTUAL? I'd expect that to scream.
> >
> > I strongly suspect this isn't going to be safe unless you always use an
> > in-place carevout from the linear map (which could be the linear alias
> > of a static carevout).
> 
> That's an excellent point, thank you! Indeed, on arm64, a version with
> naive static-pool screams with CONFIG_DEBUG_VIRTUAL.
> 
> We'll try to put together an arm64 version using a carveout as you suggest.

Great, thanks!

Just to be clear, the concerns for DMA and virt<->phys conversions also
apply to x86 (the x86 virt<->phys conversion behaviour is more forgiving
in the common case, but still has cases that can go wrong).

Other than the code to initialize the page tables for the careveout, I
think the carevout code can be geenric.

Thanks,
Mark.


  reply	other threads:[~2020-09-29 15:06 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-21 13:26 [PATCH v3 00/10] KFENCE: A low-overhead sampling-based memory safety error detector Marco Elver
2020-09-21 13:26 ` [PATCH v3 01/10] mm: add Kernel Electric-Fence infrastructure Marco Elver
2020-09-25 11:23   ` SeongJae Park
2020-09-25 11:31     ` Marco Elver
2020-09-29 12:42   ` Andrey Konovalov
2020-09-29 13:11     ` Marco Elver
2020-09-29 13:48       ` Andrey Konovalov
2020-09-29 13:49         ` Marco Elver
2020-09-29 14:01           ` Andrey Konovalov
2020-09-29 14:24   ` Mark Rutland
2020-09-29 14:51     ` Marco Elver
2020-09-29 15:05       ` Mark Rutland [this message]
2020-10-05 16:00         ` Alexander Potapenko
2020-10-05 16:49           ` Jann Horn
2020-09-29 15:51     ` Alexander Potapenko
2020-10-01 18:11       ` Mark Rutland
2020-09-21 13:26 ` [PATCH v3 02/10] x86, kfence: enable KFENCE for x86 Marco Elver
2020-09-21 13:26 ` [PATCH v3 03/10] arm64, kfence: enable KFENCE for ARM64 Marco Elver
2020-09-21 14:31   ` Will Deacon
2020-09-21 14:58     ` Alexander Potapenko
2020-09-21 15:37       ` Alexander Potapenko
2020-09-21 17:43         ` Will Deacon
2020-09-22  9:56           ` Marco Elver
2020-09-29 13:53             ` Mark Rutland
2020-09-29 16:52               ` Alexander Potapenko
2020-09-25 15:25     ` Alexander Potapenko
2020-09-29 14:02       ` Mark Rutland
2020-10-01 11:24         ` Alexander Potapenko
2020-10-01 17:57           ` Mark Rutland
2020-10-08  9:40             ` Marco Elver
2020-10-08 10:45               ` Mark Rutland
2020-10-14 19:12                 ` Marco Elver
2020-10-15 13:39                   ` Mark Rutland
2020-10-15 14:15                     ` Marco Elver
2020-09-28 11:53     ` Marco Elver
2020-09-29 14:27   ` Mark Rutland
2020-09-29 17:04     ` Alexander Potapenko
2020-09-21 13:26 ` [PATCH v3 04/10] mm, kfence: insert KFENCE hooks for SLAB Marco Elver
2020-09-21 13:26 ` [PATCH v3 05/10] mm, kfence: insert KFENCE hooks for SLUB Marco Elver
2020-09-21 13:26 ` [PATCH v3 06/10] kfence, kasan: make KFENCE compatible with KASAN Marco Elver
2020-09-29 12:20   ` Andrey Konovalov
2020-09-29 13:13     ` Alexander Potapenko
2020-09-21 13:26 ` [PATCH v3 07/10] kfence, kmemleak: make KFENCE compatible with KMEMLEAK Marco Elver
2020-09-21 13:26 ` [PATCH v3 08/10] kfence, lockdep: make KFENCE compatible with lockdep Marco Elver
2020-09-21 13:26 ` [PATCH v3 09/10] kfence, Documentation: add KFENCE documentation Marco Elver
2020-09-21 13:26 ` [PATCH v3 10/10] kfence: add test suite Marco Elver
2020-09-21 17:13   ` Paul E. McKenney
2020-09-21 17:37     ` Marco Elver
2020-09-21 17:48       ` Paul E. McKenney
2020-09-21 13:38 ` [PATCH v3 00/10] KFENCE: A low-overhead sampling-based memory safety error detector Dmitry Vyukov

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