From: Alexander Potapenko <glider@google.com>
To: Christopher Lameter <cl@linux.com>
Cc: 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>,
Dave Hansen <dave.hansen@linux.intel.com>,
David Rientjes <rientjes@google.com>,
Dmitriy Vyukov <dvyukov@google.com>,
Eric Dumazet <edumazet@google.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ingo Molnar <mingo@redhat.com>, Jann Horn <jannh@google.com>,
Jonathan.Cameron@huawei.com, Jonathan Corbet <corbet@lwn.net>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Kees Cook <keescook@chromium.org>,
Mark Rutland <mark.rutland@arm.com>,
Pekka Enberg <penberg@kernel.org>,
Peter Zijlstra <peterz@infradead.org>, Qian Cai <cai@lca.pw>,
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 v2 04/10] mm, kfence: insert KFENCE hooks for SLAB
Date: Thu, 17 Sep 2020 11:47:59 +0200 [thread overview]
Message-ID: <CAG_fn=XMc8NPZPFtUE=rdoR=XJH4F+TxZs-w5n4VuaWKTjcasw@mail.gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.22.394.2009170935020.1492@www.lameter.com>
> > static __always_inline void *
> > -slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
> > +slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, size_t orig_size,
> > unsigned long caller)
> > {
>
> The size of the object is available via a field in kmem_cache. And a
> pointer to the current kmem_cache is already passed to the function. Why
> is there a need to add an additional parameter?
That's because we want to do our best detecting bugs on
kmalloc-allocated objects.
kmalloc is using size classes, so e.g. when allocating 272 bytes the
object will be padded to 512.
As a result, placing that object at the end of the page won't really
help to detect out-of-bound accesses that are off by less than 270
bytes.
We probably need to better clarify this in the patch description.
--
Alexander Potapenko
Software Engineer
Google Germany GmbH
Erika-Mann-Straße, 33
80636 München
Geschäftsführer: Paul Manicle, Halimah DeLaine Prado
Registergericht und -nummer: Hamburg, HRB 86891
Sitz der Gesellschaft: Hamburg
next prev parent reply other threads:[~2020-09-17 9:48 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-15 13:20 [PATCH v2 00/10] KFENCE: A low-overhead sampling-based memory safety error detector Marco Elver
2020-09-15 13:20 ` [PATCH v2 01/10] mm: add Kernel Electric-Fence infrastructure Marco Elver
2020-09-17 13:26 ` Hillf Danton
2020-09-17 13:36 ` Marco Elver
2020-09-17 23:45 ` Hillf Danton
2020-09-15 13:20 ` [PATCH v2 02/10] x86, kfence: enable KFENCE for x86 Marco Elver
2020-09-15 13:20 ` [PATCH v2 03/10] arm64, kfence: enable KFENCE for ARM64 Marco Elver
2020-09-15 13:20 ` [PATCH v2 04/10] mm, kfence: insert KFENCE hooks for SLAB Marco Elver
2020-09-17 9:37 ` Christopher Lameter
2020-09-17 9:47 ` Alexander Potapenko [this message]
2020-09-15 13:20 ` [PATCH v2 05/10] mm, kfence: insert KFENCE hooks for SLUB Marco Elver
2020-09-17 9:40 ` Christopher Lameter
2020-09-17 9:51 ` Alexander Potapenko
2020-09-15 13:20 ` [PATCH v2 06/10] kfence, kasan: make KFENCE compatible with KASAN Marco Elver
2020-09-15 13:20 ` [PATCH v2 07/10] kfence, kmemleak: make KFENCE compatible with KMEMLEAK Marco Elver
2020-09-15 13:20 ` [PATCH v2 08/10] kfence, lockdep: make KFENCE compatible with lockdep Marco Elver
2020-09-15 13:20 ` [PATCH v2 09/10] kfence, Documentation: add KFENCE documentation Marco Elver
2020-09-15 13:20 ` [PATCH v2 10/10] kfence: add test suite Marco Elver
2020-09-15 13:49 ` [PATCH v2 00/10] KFENCE: A low-overhead sampling-based memory safety error detector Dmitry Vyukov
2020-09-18 11:17 ` Qian Cai
2020-09-18 11:59 ` Marco Elver
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