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=-7.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 A3757C433FE for ; Tue, 8 Dec 2020 18:33:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7492A23AA7 for ; Tue, 8 Dec 2020 18:33:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731061AbgLHScx (ORCPT ); Tue, 8 Dec 2020 13:32:53 -0500 Received: from mail.kernel.org ([198.145.29.99]:54978 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728633AbgLHScu (ORCPT ); Tue, 8 Dec 2020 13:32:50 -0500 Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607452330; bh=1jrzgTIJpW1sSBE3ZIOppEbfh6AvSKZMoSp0P40Y68Y=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=BU/L4KzCjzCyvQ/rLg2QtY/05SEsveztssPsOTsWEDvqljd1hcvPYiglLC59NDEs7 mDE+2ZtdDkkDSoaYsZGwjWxKqiWbMM9nnrQ4/1MBEf/4rIh83TiTFK/ouerzFtZl8+ mlwsB5jikzLisC5W61TDZAxB7AvVUjlVCzrfXohE0X55dG1DDc6FTRmy1uopzEhYeu pGwA4aRcPww2qYIMY3unhif/YGZ1Udd/WH+0nCEgcm+bOTQ0+eSluhi8UUVXe2lkHt IdcHdzAGAV3K1Mre8MQUox/5tsAN3XdSPu2EanwV5BgWUxdfSteeGOENQjU/d5vfAU tj4CKZP9UlH2A== Subject: Re: [PATCH v3 3/5] tracing: Update synth command errors From: Tom Zanussi To: Steven Rostedt Cc: axelrasmussen@google.com, mhiramat@kernel.org, linux-kernel@vger.kernel.org Date: Tue, 08 Dec 2020 12:32:08 -0600 In-Reply-To: <20201208125340.407150f2@gandalf.local.home> References: <8671adc7ce95ff1d5c7b037d371467e96f7f2914.1603723933.git.zanussi@kernel.org> <20201207201304.627bfe48@oasis.local.home> <44b9e471f0d3b77ab0a2bf11024e2e72c1f1a80d.camel@kernel.org> <20201208125340.407150f2@gandalf.local.home> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Steve, On Tue, 2020-12-08 at 12:53 -0500, Steven Rostedt wrote: > On Tue, 08 Dec 2020 11:34:41 -0600 > Tom Zanussi wrote: > > > Unfortunately, you're correct, if you have a script that creates a > > synthetic event without semicolons, this patchset will break it, as > > I > > myself found out and fixed in patch 4 ([PATCH v3 4/5] > > selftests/ftrace: > > Add synthetic event field separators) [4]. > > > > So whereas before this would work, even though it shouldn't have in > > the > > first place: > > > > # echo 'wakeup_latency u64 lat pid_t pid char comm[16]' > > > synthetic_events > > > > it now has to be: > > > > # echo 'wakeup_latency u64 lat; pid_t pid; char comm[16]' > > > synthetic_events > > > > So yeah, this patchset fixes a set of parsing bugs for things that > > shouldn't have been accepted as valid, but shouldn't break things > > that > > are obviously valid. > > > > If it's too late to fix them, though, I guess we'll just have to > > live > > with them, or some other option? > > > I would suggest allowing the old interface work (with no new > features, for > backward compatibility), but new things like "char comm[16]" we > require > semicolons. > > One method to do this is to add to the start of reading the string, > and > checking if it has semicolons. If it does not, we create a new string > with > them, but make sure that the string does not include new changes. > > strncpy_from_user(buffer, user_buff, sizeof(buffer)); > > if (!strstr(buffer, ";")) { > if (!audit_old_buffer(buffer)) > goto error; > insert_colons(buffer); > } > > > That is, if the buffer does not have semicolons, then check if it is > a > valid "old format", and if not, we error out. Otherwise, we insert > the > colons into the buffer, and process that as if the user put in > colons: > > That is: > > echo 'wakeup_latency u64 lat pid_t pid' > synthetic_events > > would change the buffer to: > > "wakeup_latency u64 lat; pid_t pid;" > > And then put it through the normal processing. I think its OK that if > the > user were to cat out the synthetic events, it would see the > semicolons even > if it did not add them. As I don't think that will break userspace. > > Does that make sense? > Yeah, that should work, I'll try adding that. Thanks, Tom > -- Steve