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Message-ID: <b18ca2ce-5ebc-1a38-bb9d-a8bb9070cdb1@suse.cz>
Date:   Thu, 13 Jul 2023 09:44:52 +0200
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Subject: Re: [PATCH 2/2] mm/slub: remove freelist_dereference()
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To:     Kees Cook <keescook@chromium.org>
Cc:     Christoph Lameter <cl@linux.com>,
        David Rientjes <rientjes@google.com>,
        Pekka Enberg <penberg@kernel.org>,
        Joonsoo Kim <iamjoonsoo.kim@lge.com>,
        Hyeonggon Yoo <42.hyeyoo@gmail.com>,
        Roman Gushchin <roman.gushchin@linux.dev>, linux-mm@kvack.org,
        patches@lists.linux.dev, linux-kernel@vger.kernel.org,
        Matteo Rizzo <matteorizzo@google.com>,
        Jann Horn <jannh@google.com>,
        Andrey Konovalov <andreyknvl@google.com>,
        Marco Elver <elver@google.com>,
        Alexander Potapenko <glider@google.com>,
        kasan-dev@googlegroups.com, linux-hardening@vger.kernel.org
References: <20230711134623.12695-3-vbabka@suse.cz>
 <20230711134623.12695-4-vbabka@suse.cz> <202307110917.DEED145F0@keescook>
From:   Vlastimil Babka <vbabka@suse.cz>
In-Reply-To: <202307110917.DEED145F0@keescook>
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On 7/11/23 18:21, Kees Cook wrote:
> On Tue, Jul 11, 2023 at 03:46:25PM +0200, Vlastimil Babka wrote:
>>  
>>  #ifndef CONFIG_SLUB_TINY
>> -- 
>> 2.41.0
>> 
> 
> I like reducing the complexity here, but I find dropping the "object"
> reassignment makes this a bit harder to read. What about:

Alright.

> 	object = kasan_reset_tag(object);
> 	unsigned long ptr_addr = (unsigned long)object + s->offset;
> 	freeptr_t p = *(freeptr_t *)(ptr_addr);

Are we really so benevolent with declaration-after-statement now? :)

> 	return freelist_ptr_decode(s, p, ptr_addr);
> 
> ?
> 
> They're the same result, so either way:
> 
> Acked-by: Kees Cook <keescook@chromium.org>
>