From mboxrd@z Thu Jan 1 00:00:00 1970 From: Johannes Weiner Subject: Re: [PATCH 1/2] mm, treewide: Rename kzfree() to kfree_sensitive() Date: Wed, 15 Apr 2020 01:01:06 -0400 Message-ID: <20200415050106.GA154671@cmpxchg.org> References: <20200413211550.8307-1-longman@redhat.com> <20200413211550.8307-2-longman@redhat.com> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20200413211550.8307-2-longman-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-wireless-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit 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-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, keyrings-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, x86-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-crypto-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-s390-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-stm32-XDFAJ8BFU24N7RejjzZ/Li2xQDfSxrLKVpNB7YpNyf8@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-amlogic-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linuxppc-dev-uLR06cmDAlY/bJ5BZ2RsiQ@public.gmane.org, virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, netdev@vg On Mon, Apr 13, 2020 at 05:15:49PM -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. As the btrfs example proves - people can be tempted by this false symmetry to pair kzalloc with kzfree, which isn't what we wanted. > 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 Looks good to me. Thanks for fixing this very old mistake. Acked-by: Johannes Weiner