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[195.135.220.15]) by mx.google.com with ESMTPS id ka18si2718614ejb.151.2019.06.26.07.49.45 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 26 Jun 2019 07:49:46 -0700 (PDT) Received-SPF: softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning mhocko@kernel.org does not designate 195.135.220.15 as permitted sender) smtp.mailfrom=mhocko@kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=kernel.org X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 4CFCFAC2E; Wed, 26 Jun 2019 14:49:45 +0000 (UTC) Date: Wed, 26 Jun 2019 16:49:43 +0200 From: Michal Hocko To: Alexander Potapenko Cc: Andrew Morton , Christoph Lameter , Kees Cook , Masahiro Yamada , James Morris , "Serge E. Hallyn" , Nick Desaulniers , Kostya Serebryany , Dmitry Vyukov , Sandeep Patil , Laura Abbott , Randy Dunlap , Jann Horn , Mark Rutland , Marco Elver , Qian Cai , linux-mm@kvack.org, linux-security-module@vger.kernel.org, kernel-hardening@lists.openwall.com Subject: Re: [PATCH v8 1/2] mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options Message-ID: <20190626144943.GY17798@dhcp22.suse.cz> References: <20190626121943.131390-1-glider@google.com> <20190626121943.131390-2-glider@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190626121943.131390-2-glider@google.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Wed 26-06-19 14:19:42, Alexander Potapenko wrote: [...] > diff --git a/mm/dmapool.c b/mm/dmapool.c > index 8c94c89a6f7e..fe5d33060415 100644 > --- a/mm/dmapool.c > +++ b/mm/dmapool.c [...] > @@ -428,6 +428,8 @@ void dma_pool_free(struct dma_pool *pool, void *vaddr, dma_addr_t dma) > } > > offset = vaddr - page->vaddr; > + if (want_init_on_free()) > + memset(vaddr, 0, pool->size); any reason why this is not in DMAPOOL_DEBUG else branch? Why would you want to both zero on free and poison on free? > #ifdef DMAPOOL_DEBUG > if ((dma - page->dma) != offset) { > spin_unlock_irqrestore(&pool->lock, flags); [...] > @@ -1142,6 +1200,8 @@ static __always_inline bool free_pages_prepare(struct page *page, > } > arch_free_page(page, order); > kernel_poison_pages(page, 1 << order, 0); > + if (want_init_on_free()) > + kernel_init_free_pages(page, 1 << order); same here. If you don't want to make this exclusive then you have to zero before poisoning otherwise you are going to blow up on the poison check, right? > if (debug_pagealloc_enabled()) > kernel_map_pages(page, 1 << order, 0); > -- Michal Hocko SUSE Labs