From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-3.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A84EC43613 for ; Fri, 21 Jun 2019 01:19:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E78D72084A for ; Fri, 21 Jun 2019 01:19:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="naw7755f" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726100AbfFUBTa (ORCPT ); Thu, 20 Jun 2019 21:19:30 -0400 Received: from mail-pl1-f196.google.com ([209.85.214.196]:42568 "EHLO mail-pl1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725906AbfFUBTa (ORCPT ); Thu, 20 Jun 2019 21:19:30 -0400 Received: by mail-pl1-f196.google.com with SMTP id ay6so2121786plb.9 for ; Thu, 20 Jun 2019 18:19:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=eJKYybw5a1SWYpHwymEpjHSIfv7GuhVzn0pIpamG/wM=; b=naw7755fmAIXafE+Jl7dV8RVkpTo05kib/8CyuURh0MhrDFRQHF3jVyKVS6EeiB8N9 BoFpd2iPgtOquKwlZ5rum1uAPcDMOfYH2zVtsc/BNjku12A7gon9LDPgQ+5iJ4Ko7J14 5OMRX+XjMMr1O4lr8I4IGUtO/vyhyJrLisAS0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=eJKYybw5a1SWYpHwymEpjHSIfv7GuhVzn0pIpamG/wM=; b=Bl5eIxPZK8Z6E+cZjJnXTiMHNf2fFT7G25m6FzFX3ufdtl60+eJrylh1aMmqNbI/Ba aDyR6eu43nhZ8RDLj+YwvdGuRNfenRPTdTdyo/yeDXiDwONMxScJBG8jvuKOV1yZwisz Qyzv9DjkNz211qD9Rt3lBrajDBYST4ebhB60E9yWIqijAYfO9JFOhi6MeJHE3iWbmakH xBSKTTrXt92JLZQV/+gcRwTywgGMbPzp2O5FL0TqVCVkTGBMK74nfk4UH1VWNdAZJR5K Rq6iIfNsLisaFVn9KqrYEf3LTxND9HS3OJNDUn7+TtlTIi4yN+OgjHk7cd08aM1Zc/HP QJcQ== X-Gm-Message-State: APjAAAWkB5rLFUfln+u4rLKXzOb8GSMMQEMt3+tm4Y9/O7yAc/i1w6qy DLzOYVNpAcCDoW1+lSjJSF1gJg== X-Google-Smtp-Source: APXvYqzDCGsl/sfw+DruyeiWlGEv/UbXrhWxZujE3VvkgVVndHlvNmAR1JKU/5PFrVACJM85q79/Uw== X-Received: by 2002:a17:902:968c:: with SMTP id n12mr34357353plp.59.1561079969560; Thu, 20 Jun 2019 18:19:29 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id b26sm680142pfo.129.2019.06.20.18.19.28 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Thu, 20 Jun 2019 18:19:28 -0700 (PDT) Date: Thu, 20 Jun 2019 18:19:27 -0700 From: Kees Cook To: Qian Cai Cc: akpm@linux-foundation.org, glider@google.com, cl@linux.com, penberg@kernel.org, rientjes@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH -next] slub: play init_on_free=1 well with SLAB_RED_ZONE Message-ID: <201906201818.6C90BC875@keescook> References: <1561058881-9814-1-git-send-email-cai@lca.pw> <201906201812.8B49A36@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <201906201812.8B49A36@keescook> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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(struct kmem_cache *s, > > do { > > object = next; > > next = 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.) -- Kees Cook