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=-7.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED 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 5A1BBC0044C for ; Sat, 3 Nov 2018 11:54:54 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 00CAE2082D for ; Sat, 3 Nov 2018 11:54:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="1CfJtMGV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 00CAE2082D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728416AbeKCVF4 (ORCPT ); Sat, 3 Nov 2018 17:05:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:50602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727498AbeKCVF4 (ORCPT ); Sat, 3 Nov 2018 17:05:56 -0400 Received: from devbox (NE2965lan1.rev.em-net.ne.jp [210.141.244.193]) (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 78C6E2082D; Sat, 3 Nov 2018 11:54:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1541246090; bh=xBKe5pe8FYOPUgN1VCtBU7MItXe4pXHTqbVujXIbBOc=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=1CfJtMGVIgh7qLAqC6Q3duef3ulD+gSdKzHUG6UgHyjXEWUtVKbqqaArmXa7wtwC4 DOGoGiVNG0Rw6bHacd5uoNj8OAG6kzxZq1+zGgOr2S0yAus1xWTPBiy/Q4xOxzGT3x CoUJohLGZCKYN4e9B7ytouJS145Aw/7zQQt2QnYg= Date: Sat, 3 Nov 2018 20:54:48 +0900 From: Masami Hiramatsu To: Steven Rostedt Cc: linux-kernel@vger.kernel.org Subject: Re: [BUGFIX PATCH] tracing/kprobes: Fix strpbrk() argument order Message-Id: <20181103205448.15b667077e0b72fcd6147239@kernel.org> In-Reply-To: <20181102095424.20c500ea@gandalf.local.home> References: <154108256792.2604.1816052586385217811.stgit@devbox> <20181101151014.2feccd51@gandalf.local.home> <20181102161459.86f0622bd01518a2eb06e1d5@kernel.org> <20181102095424.20c500ea@gandalf.local.home> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2 Nov 2018 09:54:24 -0400 Steven Rostedt wrote: > On Fri, 2 Nov 2018 16:14:59 +0900 > Masami Hiramatsu wrote: > > > On Thu, 1 Nov 2018 15:10:14 -0400 > > Steven Rostedt wrote: > > > > > On Thu, 1 Nov 2018 23:29:28 +0900 > > > Masami Hiramatsu wrote: > > > > > > > Fix strpbrk()'s argument order, it must pass acceptable string > > > > in 2nd argument. Note that this can cause a kernel panic where > > > > it recovers backup character to code->data. > > > > > > > > Fixes: a6682814f371 ("tracing/kprobes: Allow kprobe-events to record module symbol") > > > > Signed-off-by: Masami Hiramatsu > > > > > > Thanks Masami, > > > > > > I'm pulling this and starting to test it. > > > > Thank you! I still couldn't believe how this bug passed through the tests... > > I am too. I'm running tests with and without this patch, and the patch > doesn't appear to be making much difference. Maybe traceprobe_free_probe_arg() is silently failed. > > Then I tested with this: > > diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c > index 3ef15a6683c0..4ddafddf1343 100644 > --- a/kernel/trace/trace_probe.c > +++ b/kernel/trace/trace_probe.c > @@ -516,6 +516,7 @@ void traceprobe_free_probe_arg(struct probe_arg > *arg) kfree(code->data); > code++; > } > + printk("free arg->code %s\n", arg->code); > kfree(arg->code); > kfree(arg->name); > kfree(arg->comm); > @@ -535,11 +536,15 @@ int traceprobe_update_arg(struct probe_arg *arg) > if (code[1].op != FETCH_OP_IMM) > return -EINVAL; > > + tmp = strpbrk(code->data, "+-"); > + printk("first tmp tmp=%s\n", tmp); > tmp = strpbrk("+-", code->data); > + printk("second tmp=%s data=%s\n", tmp, > code->data); if (tmp) > c = *tmp; > ret = > traceprobe_split_symbol_offset(code->data, &offset); > + printk("third data=%s\n", code->data); > if (ret) > return ret; > > @@ -547,6 +552,7 @@ int traceprobe_update_arg(struct probe_arg *arg) > (unsigned > long)kallsyms_lookup_name(code->data); if (tmp) > *tmp = c; > + printk("forth data=%s\n", code->data); > if (!code[1].immediate) > return -ENOENT; > code[1].immediate += offset; > > And I don't see where that code->data is used elsewhere. That is, why > even bother saving the character? Would you mean parsing the symbol+offs every time is useless? It needs to solve the symbol address always because traceprobe_update_arg is called when new symbols added on the kernel (by loading modules). Hmm, maybe I can introduce a struct like struct symbol_offset { long offset; char symbol[]; }; and use it instead of parsing the symbol+offset always. Thanks, -- Masami Hiramatsu