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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_2 autolearn=ham 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 01AACC4338F for ; Wed, 18 Aug 2021 13:33:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id CDDD660F4C for ; Wed, 18 Aug 2021 13:33:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236270AbhHRNe1 (ORCPT ); Wed, 18 Aug 2021 09:34:27 -0400 Received: from mail.kernel.org ([198.145.29.99]:39160 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233722AbhHRNe1 (ORCPT ); Wed, 18 Aug 2021 09:34:27 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 5C0CE6109E; Wed, 18 Aug 2021 13:33:51 +0000 (UTC) Date: Wed, 18 Aug 2021 09:33:49 -0400 From: Steven Rostedt To: Kees Cook Cc: linux-kernel@vger.kernel.org, Ingo Molnar , "Gustavo A. R. Silva" , Greg Kroah-Hartman , Andrew Morton , 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, Rasmus Villemoes , linux-hardening@vger.kernel.org Subject: Re: [PATCH v2 50/63] tracing: Use memset_startat() to zero struct trace_iterator Message-ID: <20210818093349.3144276b@oasis.local.home> In-Reply-To: <20210818060533.3569517-51-keescook@chromium.org> References: <20210818060533.3569517-1-keescook@chromium.org> <20210818060533.3569517-51-keescook@chromium.org> X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org On Tue, 17 Aug 2021 23:05:20 -0700 Kees Cook wrote: > In preparation for FORTIFY_SOURCE performing compile-time and run-time > field bounds checking for memset(), avoid intentionally writing across > neighboring fields. > > Use memset_startat() to avoid confusing memset() about writing beyond > the target struct member. > > Cc: Steven Rostedt > Cc: Ingo Molnar > Signed-off-by: Kees Cook > --- > kernel/trace/trace.c | 4 +--- > 1 file changed, 1 insertion(+), 3 deletions(-) > > diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c > index 13587e771567..9ff8c31975cd 100644 > --- a/kernel/trace/trace.c > +++ b/kernel/trace/trace.c > @@ -6691,9 +6691,7 @@ tracing_read_pipe(struct file *filp, char __user *ubuf, > cnt = PAGE_SIZE - 1; > > /* reset all but tr, trace, and overruns */ > - memset(&iter->seq, 0, > - sizeof(struct trace_iterator) - > - offsetof(struct trace_iterator, seq)); > + memset_startat(iter, 0, seq); I can't find memset_startat() in mainline nor linux-next. I don't see it in this thread either, but since this has 63 patches, I could have easily missed it. This change really should belong to a patch set that just introduces memset_startat() (and perhaps memset_after()) and then updates all the places that should use it. That way I can give it a proper review. In other words, you should break this patch set up into smaller, more digestible portions for the reviewers. Thanks, -- Steve > cpumask_clear(iter->started); > trace_seq_init(&iter->seq); > iter->pos = -1;