From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.220.28]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A4A272 for ; Mon, 9 Aug 2021 11:32:58 +0000 (UTC) Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out1.suse.de (Postfix) with ESMTP id 6D8F421ED4; Mon, 9 Aug 2021 11:23:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_rsa; t=1628508202; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XEHaigBd+p4Kdq3FOyfyiQahnEWWgwrbyI9p3sYy9Jg=; b=FUJg+QaU7zw3qTf6t8q9Qr96X0Utqfsl+nS4wyhc9/5vWZMS539Of9T5SM02pWzim1Cnda RMrFBB4C9IiCbCzLy7hKe0Nw5kCTqLiYUG2RwoYyBydeMv59tIlgL5Vpa/xsWEDauKkWvj 09N1MMAWFSlJkFOi7ijKkWYVWovvXhs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.cz; s=susede2_ed25519; t=1628508202; h=from:from:reply-to:reply-to:date:date:message-id:message-id:to:to: cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=XEHaigBd+p4Kdq3FOyfyiQahnEWWgwrbyI9p3sYy9Jg=; b=4VeRarVySJZv/AlngzeBW/O6mbVTRAHHGwmwBsPvaCbeLhv85RY/VfIGPtUkorqnnpUTKq o+aHpptVRlTrrwAw== Received: from ds.suse.cz (ds.suse.cz [10.100.12.205]) by relay2.suse.de (Postfix) with ESMTP id 53C44A3B8E; Mon, 9 Aug 2021 11:23:22 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id BAE5EDA880; Mon, 9 Aug 2021 13:20:30 +0200 (CEST) Date: Mon, 9 Aug 2021 13:20:30 +0200 From: David Sterba To: Kees Cook Cc: linux-hardening@vger.kernel.org, "Gustavo A. R. Silva" , Keith Packard , Greg Kroah-Hartman , Andrew Morton , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH 47/64] btrfs: Use memset_after() to clear end of struct Message-ID: <20210809112030.GM5047@suse.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Kees Cook , linux-hardening@vger.kernel.org, "Gustavo A. R. Silva" , Keith Packard , Greg Kroah-Hartman , Andrew Morton , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com References: <20210727205855.411487-1-keescook@chromium.org> <20210727205855.411487-48-keescook@chromium.org> <20210728094215.GX5047@twin.jikos.cz> <202107281455.2A0753F5@keescook> <20210729103337.GS5047@suse.cz> <202107310822.31BEB6E543@keescook> Precedence: bulk X-Mailing-List: linux-staging@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <202107310822.31BEB6E543@keescook> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) On Sat, Jul 31, 2021 at 08:25:51AM -0700, Kees Cook wrote: > On Thu, Jul 29, 2021 at 12:33:37PM +0200, David Sterba wrote: > > On Wed, Jul 28, 2021 at 02:56:31PM -0700, Kees Cook wrote: > > > On Wed, Jul 28, 2021 at 11:42:15AM +0200, David Sterba wrote: > > > > On Tue, Jul 27, 2021 at 01:58:38PM -0700, Kees Cook wrote: > > > > > } > > > > > if (need_reset) { > > > > > - memset(&item->generation_v2, 0, > > > > > - sizeof(*item) - offsetof(struct btrfs_root_item, > > > > > - generation_v2)); > > > > > - > > > > > > > > Please add > > > > /* Clear all members from generation_v2 onwards */ > > > > > > > > > + memset_after(item, 0, level); > > > > > > Perhaps there should be another helper memset_starting()? That would > > > make these cases a bit more self-documenting. > > > > That would be better, yes. > > > > > + memset_starting(item, 0, generation_v2); > > > > memset_from? > > For v2, I bikeshed this to "memset_startat" since "from" is semantically > close to "source" which I thought might be confusing. (I, too, did not > like "starting".) :) memset_startat works for me, thanks.