From: Feng Tang <feng.tang@intel.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
"Dmitry Vyukov" <dvyukov@google.com>,
Andrey Konovalov <andreyknvl@gmail.com>,
"Kees Cook" <keescook@chromium.org>,
"Hansen, Dave" <dave.hansen@intel.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>
Subject: Re: [PATCH v7 1/3] mm/slub: only zero requested size of buffer for kzalloc when debug enabled
Date: Fri, 11 Nov 2022 14:19:47 +0800 [thread overview]
Message-ID: <Y23pgyz32TRsAskz@feng-clx> (raw)
In-Reply-To: <eaf74c95-6641-8785-61f6-c7013c2f55eb@suse.cz>
On Thu, Nov 10, 2022 at 04:44:59PM +0100, Vlastimil Babka wrote:
> On 11/10/22 13:57, Feng Tang wrote:
> > On Thu, Nov 10, 2022 at 11:20:34AM +0800, Tang, Feng wrote:
> >> On Wed, Nov 09, 2022 at 03:28:19PM +0100, Vlastimil Babka wrote:
> > [...]
> >> > > + /*
> >> > > + * For kmalloc object, the allocated memory size(object_size) is likely
> >> > > + * larger than the requested size(orig_size). If redzone check is
> >> > > + * enabled for the extra space, don't zero it, as it will be redzoned
> >> > > + * soon. The redzone operation for this extra space could be seen as a
> >> > > + * replacement of current poisoning under certain debug option, and
> >> > > + * won't break other sanity checks.
> >> > > + */
> >> > > + if (kmem_cache_debug_flags(s, SLAB_STORE_USER) &&
> >> >
> >> > Shouldn't we check SLAB_RED_ZONE instead? Otherwise a debugging could be
> >> > specified so that SLAB_RED_ZONE is set but SLAB_STORE_USER?
> >>
> >> Thanks for the catch!
> >>
> >> I will add check for SLAB_RED_ZONE. The SLAB_STORE_USER is for
> >> checking whether 'orig_size' field exists. In earlier discussion,
> >> we make 'orig_size' depend on STORE_USER, https://lore.kernel.org/lkml/1b0fa66c-f855-1c00-e024-b2b823b18678@suse.cz/
> >
> > Below is the updated patch, please review, thanks!
>
> Thanks, grabbing it including Andrey's review, with a small change below:
>
> > - Feng
> >
> > -----8>----
> > From b2a92f0c2518ef80fcda340f1ad37b418ee32d85 Mon Sep 17 00:00:00 2001
> > From: Feng Tang <feng.tang@intel.com>
> > Date: Thu, 20 Oct 2022 20:47:31 +0800
> > Subject: [PATCH 1/3] mm/slub: only zero requested size of buffer for kzalloc
> > when debug enabled
[...]
> > + /*
> > + * For kmalloc object, the allocated memory size(object_size) is likely
> > + * larger than the requested size(orig_size). If redzone check is
> > + * enabled for the extra space, don't zero it, as it will be redzoned
> > + * soon. The redzone operation for this extra space could be seen as a
> > + * replacement of current poisoning under certain debug option, and
> > + * won't break other sanity checks.
> > + */
> > + if (kmem_cache_debug_flags(s, SLAB_STORE_USER) &&
> > + (s->flags & SLAB_RED_ZONE) &&
>
> Combined the two above to:
>
> if (kmem_cache_debug_flags(s, SLAB_STORE_USER | SLAB_RED_ZONE)
Yes, this is cleaner, thanks!
- Feng
next prev parent reply other threads:[~2022-11-11 6:23 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-10-21 3:24 [PATCH v7 0/3] mm/slub: extend redzone check for kmalloc objects Feng Tang
2022-10-21 3:24 ` [PATCH v7 1/3] mm/slub: only zero requested size of buffer for kzalloc when debug enabled Feng Tang
2022-10-24 14:00 ` Hyeonggon Yoo
2022-10-27 19:27 ` Andrey Konovalov
2022-11-09 14:28 ` Vlastimil Babka
2022-11-10 3:20 ` Feng Tang
2022-11-10 12:57 ` Feng Tang
2022-11-10 15:44 ` Vlastimil Babka
2022-11-11 6:19 ` Feng Tang [this message]
2022-10-21 3:24 ` [PATCH v7 2/3] mm: kasan: Extend kasan_metadata_size() to also cover in-object size Feng Tang
2022-10-27 19:27 ` Andrey Konovalov
2022-10-21 3:24 ` [PATCH v7 3/3] mm/slub: extend redzone check to extra allocated kmalloc space than requested Feng Tang
2022-11-10 15:48 ` Vlastimil Babka
2022-11-11 6:46 ` Feng Tang
2022-11-11 8:12 ` Vlastimil Babka
2022-11-11 8:16 ` [PATCH v7 0/3] mm/slub: extend redzone check for kmalloc objects Vlastimil Babka
2022-11-11 8:29 ` Feng Tang
2022-11-21 6:38 ` Feng Tang
2022-11-23 9:48 ` Vlastimil Babka
2022-11-28 5:43 ` Feng Tang
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