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From: Kees Cook <kees@kernel.org>
To: Feng Tang <feng.tang@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>, Marco Elver <elver@google.com>,
	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>,
	Andrey Konovalov <andreyknvl@gmail.com>,
	Shuah Khan <skhan@linuxfoundation.org>,
	David Gow <davidgow@google.com>,
	Danilo Krummrich <dakr@kernel.org>,
	Alexander Potapenko <glider@google.com>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	Vincenzo Frascino <vincenzo.frascino@arm.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	"kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	Eric Dumazet <edumazet@google.com>
Subject: Re: [PATCH v2 0/5] mm/slub: Improve data handling of krealloc() when orig_size is enabled
Date: Mon, 14 Oct 2024 13:40:01 -0700	[thread overview]
Message-ID: <202410141338.EA1D30F3@keescook> (raw)
In-Reply-To: <Zw0otGNgqPUeTdWJ@feng-clx.sh.intel.com>

On Mon, Oct 14, 2024 at 10:20:36PM +0800, Feng Tang wrote:
> On Mon, Oct 14, 2024 at 03:12:09PM +0200, Vlastimil Babka wrote:
> > On 10/14/24 14:52, Feng Tang wrote:
> > > On Mon, Oct 14, 2024 at 10:53:32AM +0200, Vlastimil Babka wrote:
> > >> On 10/14/24 09:52, Feng Tang wrote:
> > > OK, originally I tried not to expose internals of __ksize(). Let me
> > > try this way.
> > 
> > ksize() makes assumptions that a user outside of slab itself is calling it.
> > 
> > But we (well mostly Kees) also introduced kmalloc_size_roundup() to avoid
> > querying ksize() for the purposes of writing beyond the original
> > kmalloc(size) up to the bucket size. So maybe we can also investigate if the
> > skip_orig_size_check() mechanism can be removed now?
> 
> I did a quick grep, and fortunately it seems that the ksize() user are
> much less than before. We used to see some trouble in network code, which
> is now very clean without the need to skip orig_size check. Will check
> other call site later.

Right -- only things that are performing a reallocation should be using
ksize(). e.g. see __slab_build_skb()

-- 
Kees Cook


  reply	other threads:[~2024-10-14 20:40 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-09-11  6:45 Feng Tang
2024-09-11  6:45 ` [PATCH v2 1/5] mm/kasan: Don't store metadata inside kmalloc object when slub_debug_orig_size is on Feng Tang
2024-09-11  6:45 ` [PATCH v2 2/5] mm/slub: Consider kfence case for get_orig_size() Feng Tang
2024-09-11  6:45 ` [PATCH v2 3/5] mm/slub: Move krealloc() and related code to slub.c Feng Tang
2024-09-11  6:45 ` [PATCH v2 4/5] mm/slub: Improve redzone check and zeroing for krealloc() Feng Tang
2024-09-11  6:45 ` [PATCH v2 5/5] mm/slub, kunit: Add testcase for krealloc redzone and zeroing Feng Tang
2024-10-02 10:42 ` [PATCH v2 0/5] mm/slub: Improve data handling of krealloc() when orig_size is enabled Vlastimil Babka
2024-10-04  6:44   ` Marco Elver
2024-10-04  9:18     ` Vlastimil Babka
2024-10-04  9:52       ` Vlastimil Babka
2024-10-04 10:28         ` Feng Tang
2024-10-14  7:52         ` Feng Tang
2024-10-14  8:53           ` Vlastimil Babka
2024-10-14 12:52             ` Feng Tang
2024-10-14 13:12               ` Vlastimil Babka
2024-10-14 14:20                 ` Feng Tang
2024-10-14 20:40                   ` Kees Cook [this message]
2024-11-04 11:28                   ` Feng Tang
2024-11-04 11:45                     ` Vlastimil Babka
2024-11-04 12:37                       ` Feng Tang
2024-10-14 20:35                 ` Kees Cook

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