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[209.85.220.65]) by mx.google.com with SMTPS id q19sor4492765vkq.52.2019.06.25.09.16.55 for (Google Transport Security); Tue, 25 Jun 2019 09:16:55 -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=lfU+EkDA; 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=bxHs3cMUSY/lcnTBaWC9lm65VMyS9xe/CNCPh9Pq+7Y=; b=lfU+EkDAWcPLRsWFZdyEfPOrokoZXTJOFAaKyF3r6LE750Q13wN0o6eV2p2X6/qNh3 xlGQrTOAWphdM3tf5Q34V9WcKc5qb9CS3qnIXd4/GggBxU4ZWYv8/urgyGIE/WjwL9wu JBhXvzUzCj7LzikrH2PdogJbPcFyLBQSVovo2yg69817e8gHinU5WNLuBem3pzfcgKhm uwj1XNHUc/4wK7wKWvtPAIKoXhNIipBITpomNKuKYvub+6wZ7z9/OKSUdHzocg5uIVxn gjVsMiEuEbdySUgXhOjJfMxL6lLkNNocT19B5soH7h9dL3yAl4V0IUneDji3O4ZE3idz OLlA== X-Google-Smtp-Source: APXvYqzpmnLCOXbPK1tWPjNlTXEyP5BOMbJ27cXAFZ8jzDcM35yx9cTomQz6y6wya6Cj0FLuD1+b0URocoD+vFFBtcY= X-Received: by 2002:a1f:b0b:: with SMTP id 11mr6742950vkl.64.1561479415224; Tue, 25 Jun 2019 09:16:55 -0700 (PDT) MIME-Version: 1.0 References: <1561058881-9814-1-git-send-email-cai@lca.pw> <201906201812.8B49A36@keescook> <201906201818.6C90BC875@keescook> <1561121745.5154.37.camel@lca.pw> In-Reply-To: <1561121745.5154.37.camel@lca.pw> From: Alexander Potapenko Date: Tue, 25 Jun 2019 18:16:43 +0200 Message-ID: Subject: Re: [PATCH -next] slub: play init_on_free=1 well with SLAB_RED_ZONE To: Qian Cai Cc: Kees Cook , Andrew Morton , Christoph Lameter , Pekka Enberg , David Rientjes , Linux Memory Management List , LKML 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, Jun 21, 2019 at 2:55 PM Qian Cai wrote: > > On Thu, 2019-06-20 at 18:19 -0700, Kees Cook wrote: > > On Thu, Jun 20, 2019 at 06:14:33PM -0700, Kees Cook wrote: > > > On Thu, Jun 20, 2019 at 03:28:01PM -0400, Qian Cai wrote: > > > > diff --git a/mm/slub.c b/mm/slub.c > > > > index a384228ff6d3..787971d4fa36 100644 > > > > --- a/mm/slub.c > > > > +++ b/mm/slub.c > > > > @@ -1437,7 +1437,7 @@ static inline bool slab_free_freelist_hook(st= ruct > > > > kmem_cache *s, > > > > do { > > > > object =3D next; > > > > next =3D get_freepointer(s, object); > > > > - memset(object, 0, s->size); > > > > + memset(object, 0, s->object_size); > > > > > > I think this should be more dynamic -- we _do_ want to wipe all > > > of object_size in the case where it's just alignment and padding > > > adjustments. If redzones are enabled, let's remove that portion only. > > > > (Sorry, I meant: all of object's "size", not object_size.) > > > > I suppose Alexander is going to revise the series anyway, so he can proba= bly > take care of the issue here in the new version as well. Something like th= is, > > memset(object, 0, s->object_size); > memset(object, 0, s->size - s->inuse); Looks like we also need to account for the redzone size. I'm testing the fix right now. -- 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