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[209.85.220.65]) by mx.google.com with SMTPS id h4sor3122299vkh.29.2019.05.17.07.39.04 for (Google Transport Security); Fri, 17 May 2019 07:39:04 -0700 (PDT) Received-SPF: pass (google.com: domain of glider@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=ZfCTHd4n; spf=pass (google.com: domain of glider@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=glider@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=ddYknnyy251jUXjF119a2VyFqAoO0MJ7lwXqU8aG9CY=; b=ZfCTHd4njmwJ6LmyMIrWpboajTklaeBflvOkckUG57zSTiCO9V6zZ/F4wxPdk/qNUQ PVYMluJEt88jyugSzqc0nG7UZR7DLvqpFQzEFftB05/78KyrZltNrXCTTPfD64+BZVrD petSewDBThIM52+IEcDFxCTrwU4XGvwQzXx2OnY7RGaGl7FzEu9k9MeOMqSnQQ9BAkCW oGVCwrkpIb4glulSXJTh+pRPJrqZboKu7VuIf2urRTJSx9c6Q/Pq/jAHZhhJ81Od6+24 +t1zJKIIPbGUXy6ajnaWTV/1OoHtLOlwMLRNj475X7xcV2GizLUQNcqPSE4CshTe69LP g0xQ== X-Google-Smtp-Source: APXvYqzmJFfH7vnjyDXwEt0PEao3F5jTjrlEKGaCN9GO7PVaS+H8433b6AZMGQxWDooobwXiz1H5CeN39cIPFc6Nv50= X-Received: by 2002:a1f:ae4b:: with SMTP id x72mr2631730vke.29.1558103943898; Fri, 17 May 2019 07:39:03 -0700 (PDT) MIME-Version: 1.0 References: <20190514143537.10435-1-glider@google.com> <20190514143537.10435-2-glider@google.com> <201905161824.63B0DF0E@keescook> In-Reply-To: <201905161824.63B0DF0E@keescook> From: Alexander Potapenko Date: Fri, 17 May 2019 16:38:51 +0200 Message-ID: Subject: Re: [PATCH v2 1/4] mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options To: Kees Cook Cc: Andrew Morton , Christoph Lameter , Kernel Hardening , Masahiro Yamada , James Morris , "Serge E. Hallyn" , Nick Desaulniers , Kostya Serebryany , Dmitry Vyukov , Sandeep Patil , Laura Abbott , Randy Dunlap , Jann Horn , Mark Rutland , Linux Memory Management List , linux-security-module Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable 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 Fri, May 17, 2019 at 3:26 AM Kees Cook wrote: > > On Tue, May 14, 2019 at 04:35:34PM +0200, Alexander Potapenko wrote: > > [...] > > diff --git a/mm/slab.h b/mm/slab.h > > index 43ac818b8592..24ae887359b8 100644 > > --- a/mm/slab.h > > +++ b/mm/slab.h > > @@ -524,4 +524,20 @@ static inline int cache_random_seq_create(struct k= mem_cache *cachep, > > [...] > > +static inline bool slab_want_init_on_free(struct kmem_cache *c) > > +{ > > + if (static_branch_unlikely(&init_on_free)) > > + return !(c->ctor); > > BTW, why is this checking for c->ctor here? Shouldn't it not matter for > the free case? It does matter, see e.g. the handling of __OBJECT_POISON in slub.c If we just return true here, the kernel crashes. > > + else > > + return false; > > +} > > -- > Kees Cook --=20 Alexander Potapenko Software Engineer Google Germany GmbH Erika-Mann-Stra=C3=9Fe, 33 80636 M=C3=BCnchen Gesch=C3=A4ftsf=C3=BChrer: Paul Manicle, Halimah DeLaine Prado Registergericht und -nummer: Hamburg, HRB 86891 Sitz der Gesellschaft: Hamburg