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=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 E1779C433E0 for ; Tue, 16 Jun 2020 18:10:06 +0000 (UTC) Received: from krantz.zx2c4.com (krantz.zx2c4.com [192.95.5.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6EE752080D for ; Tue, 16 Jun 2020 18:10:06 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="IhpS1taE" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6EE752080D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=wireguard-bounces@lists.zx2c4.com Received: by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 7e53b455; Tue, 16 Jun 2020 17:51:50 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTPS id 6543149e (TLSv1.2:ECDHE-RSA-AES256-GCM-SHA384:256:NO) for ; Tue, 16 Jun 2020 17:51:47 +0000 (UTC) Received: from X1 (nat-ab2241.sltdut.senawave.net [162.218.216.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id B1C752082F; Tue, 16 Jun 2020 18:09:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592330985; bh=EsakDvGUztRiSNfngaRB05ekQqGnOvB3NF6mY788udI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=IhpS1taEKqV/HMmc2XrgBi59GfE8vYAI/pSBHLIEb5BHt2RggHWNsr0WFiFcGuzEE 26ygFhe/LhgEOm51069QA1LMXoAUoV3VgfH3hA2EmK0pi7/AYapihuVVI1Xsu8eHU8 MrJlU2uhSFUs9V1K5UBwvjYjOiJtcqNT5s8lHh0I= Date: Tue, 16 Jun 2020 11:09:44 -0700 From: Andrew Morton To: Waiman Long Cc: David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Linus Torvalds , Joe Perches , Matthew Wilcox , David Rientjes , Michal Hocko , Johannes Weiner , Dan Carpenter , "Jason A . Donenfeld" , linux-mm@kvack.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, linux-pm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-amlogic@lists.infradead.org, linux-mediatek@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-ppp@vger.kernel.org, wireguard@lists.zx2c4.com, linux-wireless@vger.kernel.org, devel@driverdev.osuosl.org, linux-scsi@vger.kernel.org, target-devel@vger.kernel.org, linux-cifs@vger.kernel.org, linux-fscrypt@vger.kernel.org, ecryptfs@vger.kernel.org, kasan-dev@googlegroups.com, linux-bluetooth@vger.kernel.org, linux-wpan@vger.kernel.org, linux-sctp@vger.kernel.org, linux-nfs@vger.kernel.org, tipc-discussion@lists.sourceforge.net, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org Subject: Re: [PATCH v5 2/2] mm, treewide: Rename kzfree() to kfree_sensitive() Message-Id: <20200616110944.c13f221e5c3f54e775190afe@linux-foundation.org> In-Reply-To: <20200616154311.12314-3-longman@redhat.com> References: <20200616154311.12314-1-longman@redhat.com> <20200616154311.12314-3-longman@redhat.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.30rc1 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" On Tue, 16 Jun 2020 11:43:11 -0400 Waiman Long wrote: > As said by Linus: > > A symmetric naming is only helpful if it implies symmetries in use. > Otherwise it's actively misleading. > > In "kzalloc()", the z is meaningful and an important part of what the > caller wants. > > In "kzfree()", the z is actively detrimental, because maybe in the > future we really _might_ want to use that "memfill(0xdeadbeef)" or > something. The "zero" part of the interface isn't even _relevant_. > > The main reason that kzfree() exists is to clear sensitive information > that should not be leaked to other future users of the same memory > objects. > > Rename kzfree() to kfree_sensitive() to follow the example of the > recently added kvfree_sensitive() and make the intention of the API > more explicit. In addition, memzero_explicit() is used to clear the > memory to make sure that it won't get optimized away by the compiler. > > The renaming is done by using the command sequence: > > git grep -w --name-only kzfree |\ > xargs sed -i 's/\bkzfree\b/kfree_sensitive/' > > followed by some editing of the kfree_sensitive() kerneldoc and adding > a kzfree backward compatibility macro in slab.h. > > ... > > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -186,10 +186,12 @@ void memcg_deactivate_kmem_caches(struct mem_cgroup *, struct mem_cgroup *); > */ > void * __must_check krealloc(const void *, size_t, gfp_t); > void kfree(const void *); > -void kzfree(const void *); > +void kfree_sensitive(const void *); > size_t __ksize(const void *); > size_t ksize(const void *); > > +#define kzfree(x) kfree_sensitive(x) /* For backward compatibility */ > + What was the thinking here? Is this really necessary? I suppose we could keep this around for a while to ease migration. But not for too long, please.