From: Jann Horn <jannh@google.com>
To: Alexander Potapenko <glider@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>,
Marco Elver <elver@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
"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>,
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: Mon, 5 Oct 2020 18:49:23 +0200 [thread overview]
Message-ID: <CAG48ez3kmvvymiCemX_U1=CoRrn2Ayx1fbwAzPQ2jNE-qfj4MA@mail.gmail.com> (raw)
In-Reply-To: <CAG_fn=WKEtVSRLASSZV1A9dnPGoaZM_DgJeH5Q1WcLcFBqH00g@mail.gmail.com>
On Mon, Oct 5, 2020 at 6:01 PM Alexander Potapenko <glider@google.com> wrote:
>
> On Tue, Sep 29, 2020 at 5:06 PM Mark Rutland <mark.rutland@arm.com> wrote:
> >
> > 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).
>
> To clarify, shouldn't kmalloc/kmem_cache allocations used with DMA be
> allocated with explicit GFP_DMA?
> If so, how practical would it be to just skip such allocations in
> KFENCE allocator?
AFAIK GFP_DMA doesn't really mean "I will use this allocation for
DMA"; it means "I will use this allocation for DMA using some ancient
hardware (e.g. stuff on the ISA bus?) that only supports 16-bit
physical addresses (or maybe different limits on other
architectures)".
There's also GFP_DMA32, which means the same thing, except with 32-bit
physical addresses.
You can see in e.g. __dma_direct_alloc_pages() that the GFP_DMA32 and
GFP_DMA flags are only used if the hardware can't address the full
physical address space supported by the CPU.
next prev parent reply other threads:[~2020-10-05 16:49 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
2020-10-05 16:00 ` Alexander Potapenko
2020-10-05 16:49 ` Jann Horn [this message]
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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CAG48ez3kmvvymiCemX_U1=CoRrn2Ayx1fbwAzPQ2jNE-qfj4MA@mail.gmail.com' \
--to=jannh@google.com \
--cc=Jonathan.Cameron@huawei.com \
--cc=akpm@linux-foundation.org \
--cc=andreyknvl@google.com \
--cc=aryabinin@virtuozzo.com \
--cc=bp@alien8.de \
--cc=catalin.marinas@arm.com \
--cc=cl@linux.com \
--cc=corbet@lwn.net \
--cc=dave.hansen@linux.intel.com \
--cc=dvyukov@google.com \
--cc=edumazet@google.com \
--cc=elver@google.com \
--cc=glider@google.com \
--cc=gregkh@linuxfoundation.org \
--cc=hdanton@sina.com \
--cc=hpa@zytor.com \
--cc=iamjoonsoo.kim@lge.com \
--cc=kasan-dev@googlegroups.com \
--cc=keescook@chromium.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-doc@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=luto@kernel.org \
--cc=mark.rutland@arm.com \
--cc=mingo@redhat.com \
--cc=paulmck@kernel.org \
--cc=penberg@kernel.org \
--cc=peterz@infradead.org \
--cc=rientjes@google.com \
--cc=sjpark@amazon.com \
--cc=tglx@linutronix.de \
--cc=vbabka@suse.cz \
--cc=will@kernel.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).