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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <56c2304c-73cc-8f48-d8d0-5dd6c39f33f3@redhat.com> References: <56c2304c-73cc-8f48-d8d0-5dd6c39f33f3@redhat.com> <20200616015718.7812-1-longman@redhat.com> <20200616015718.7812-2-longman@redhat.com> <20200616033035.GB902@sol.localdomain> To: Waiman Long Cc: Andrew Morton , ebiggers@kernel.org, David Howells , Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Linus Torvalds , Joe Perches , Matthew Wilcox , David Rientjes , Michal Hocko , Johannes Weiner , Dan Carpenter , David Sterba , "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-btrfs@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, stable@vger.kernel.org Subject: Re: [PATCH v4 1/3] mm/slab: Use memzero_explicit() in kzfree() MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <879078.1592322400.1@warthog.procyon.org.uk> Date: Tue, 16 Jun 2020 16:46:40 +0100 Message-ID: <879079.1592322400@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 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" Waiman Long wrote: > The kzfree() function is normally used to clear some sensitive > information, like encryption keys, in the buffer before freeing it back > to the pool. Memset() "memset()" is all lowercase. > is currently used for buffer clearing. However unlikely, there is still a > non-zero probability I'd say "a possibility". > that and I'd move "in [the] future" here. > the compiler may choose to optimize away the > memory clearing especially if LTO is being used in the future. To make sure > that this optimization will never happen "in these cases" > , memzero_explicit(), which is introduced in v3.18, is now used in "instead of"? > kzfree() to future-proof it. Davod