From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751988AbeBEWyn (ORCPT ); Mon, 5 Feb 2018 17:54:43 -0500 Received: from mail.kernel.org ([198.145.29.99]:56392 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751575AbeBEWyg (ORCPT ); Mon, 5 Feb 2018 17:54:36 -0500 DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BECD220B80 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=rostedt@goodmis.org Date: Mon, 5 Feb 2018 17:54:33 -0500 From: Steven Rostedt To: Masami Hiramatsu Cc: Al Viro , Dmitry Safonov <0x7f454c46@gmail.com>, open list Subject: Re: [RFC] apparent bogosity in unregister_ftrace_function_probe_func() Message-ID: <20180205175433.6cd369db@gandalf.local.home> In-Reply-To: <20180129225942.f2aec926e2ea223c52c34169@kernel.org> References: <20180127031706.GE13338@ZenIV.linux.org.uk> <20180127170748.GF13338@ZenIV.linux.org.uk> <20180129225942.f2aec926e2ea223c52c34169@kernel.org> X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 29 Jan 2018 22:59:42 +0900 Masami Hiramatsu wrote: > On Sat, 27 Jan 2018 17:07:48 +0000 > Al Viro wrote: > > > On Sat, Jan 27, 2018 at 01:59:56PM +0000, Dmitry Safonov wrote: > > > > > > > Incidentally, shouldn't filter_parse_regex("*[ab]", 5, &s, ¬) > > > > end up with s = "*[ab]"? We are returning MATCH_GLOB, after all, > > > > so we want the entire pattern there... I would've assumed that > > > > this is what the code in unregister_ftrace_function_probe_func() > > > > is trying to compensate for, the first oddity predates MATCH_GLOB... > > > > > > No, I don't think filter_parse_regex() should return the full regex.. > > > ftrace_match() expects search would be processed string, not a glob. > > > So, this unnecessary assignment broke unregistering multiple kprobs > > > with a middle/end pattern.. > > > > For substring - sure, but what about something like "*a*b" and "a*b"? > > AFAICS, filter_parse_regex() ends up with identical results in both > > cases - MATCH_GLOB and *search = "a*b". And no way for the caller > > to tell one from another. > > > > IOW, it's a different bug sometimes obscured by the one in > > unregister_ftrace_function_probe_func(). filter_parse_regex() > > ought to revert to *search = buff; when it decides to return > > MATCH_GLOB. Or something like > > for (i = 0; i < len; i++) { > > if (buff[i] == '*') { > > if (!i) { > > type = MATCH_END_ONLY; > > } else if (i == len - 1) { > > if (type == MATCH_END_ONLY) > > type = MATCH_MIDDLE_ONLY; > > else > > type = MATCH_FRONT_ONLY; > > buff[i] = 0; > > break; > > } else { /* pattern continues, use full glob */ > > return MATCH_GLOB; > > } > > } else if (strchr("[?\\", buff[i])) { > > return MATCH_GLOB; > > } > > } > > if (buff[0] == '*') > > *search = buff + 1; > > for that matter - i.e. delay that "we want everything past the first character" > > until we are certain it's not a MATCH_GLOB. > > Looks nice to me! > I'll implement this code giving Al credit and referencing this email thread. Anyone have objections to that? Thanks! -- Steve