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Thu, 13 Jul 2023 07:44:52 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id 9qF4IXSrr2QVFgAAMHmgww (envelope-from ); Thu, 13 Jul 2023 07:44:52 +0000 Message-ID: Date: Thu, 13 Jul 2023 09:44:52 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.13.0 Subject: Re: [PATCH 2/2] mm/slub: remove freelist_dereference() Content-Language: en-US To: Kees Cook Cc: Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Roman Gushchin , linux-mm@kvack.org, patches@lists.linux.dev, linux-kernel@vger.kernel.org, Matteo Rizzo , Jann Horn , Andrey Konovalov , Marco Elver , Alexander Potapenko , 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 In-Reply-To: <202307110917.DEED145F0@keescook> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: kdrmy9qyd8y8frtdomcgwaeoj88m18nx X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 5875220011 X-Rspam-User: X-HE-Tag: 1689234294-323899 X-HE-Meta: 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 AuSmOBDr cewJdl0w++GC+7pirr1BUyNJSSUDFoCCccUzb7h3c8sDatLf7Iy6Qu1oliVbO0JxCiT4b+dooQd++GeiX5fhtbW6AH996NFjjuwDjjOEWmkq3zzYeFuI8HeOE+u+f4qNhihtBNipv5jTZ7o9DUULgkXJ9NRpJyhGNpVWVxC/jAFd95aeoIL967PcW8oHFlcGEybboY+aZjABWG6EnwsJQpm4QBoMLmoAXugQcRh8kauDGiu6mh4qDRH8J5PzFefSTnRzAf8krFcUPID7GOwMaZMp/G6GmlibnS0mCyC5ctws4gO75omAnU6VOzTCFyX7Al5M5lEh7UzfVMnjEYulxjfHeuqPhncmBujm7P3ui2WqlknhkhYldLJS2EQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 >