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[37.188.180.223]) by smtp.gmail.com with ESMTPSA id n6sm18637096wrs.81.2020.04.14.02.01.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Apr 2020 02:01:30 -0700 (PDT) Date: Tue, 14 Apr 2020 11:01:29 +0200 From: Michal Hocko To: Waiman Long Cc: Andrew Morton , David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Linus Torvalds , Joe Perches , Matthew Wilcox , David Rientjes , linux-mm@kvack.org, keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, x86@kernel.org, linux-crypto@vger.kernel.org, linux-s390@vger.kernel.org, linux-pm@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-amlogic@lists.infradead.org, linux-mediatek@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, intel-wired-lan@lists.osuosl.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-btrfs@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.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, cocci@systeme.lip6.fr, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org Subject: Re: [PATCH 1/2] mm, treewide: Rename kzfree() to kfree_sensitive() Message-ID: <20200414090129.GE4629@dhcp22.suse.cz> References: <20200413211550.8307-1-longman@redhat.com> <20200413211550.8307-2-longman@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200413211550.8307-2-longman@redhat.com> Sender: linux-fscrypt-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fscrypt@vger.kernel.org On Mon 13-04-20 17:15:49, 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 the > use of memzero_explicit() instead of memset(). > > Suggested-by: Joe Perches > Signed-off-by: Waiman Long Makes sense. I haven't checked all the conversions and will rely on the script doing the right thing. The core MM part is correct. Acked-by: Michal Hocko -- Michal Hocko SUSE Labs