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=-1.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,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 90AD1C169C4 for ; Wed, 6 Feb 2019 04:41:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5C43A218A3 for ; Wed, 6 Feb 2019 04:41:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549428083; bh=/VHxJyIBpRzCH+yqtI/5Hc0l7YU9N4pdah5ExIwuEy0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=xGQgRb03GW8lmU3TPESpjZ8to9k0l5bwlzDeTvX0WS6aik7S7PrQGcN4kDIgnFz7F Xne+3ATn2sZyPr5GemOIJ8emJvWgfog1jd3U1YWmxvT93Kp7EIHbokBR8Mn8icAMw/ mj3k6/eDZV4VF000CgqYZWFVYUU9m5R2OdbIQu+Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727469AbfBFElT (ORCPT ); Tue, 5 Feb 2019 23:41:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:46656 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727068AbfBFElT (ORCPT ); Tue, 5 Feb 2019 23:41:19 -0500 Received: from devnote (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 525DA218A1; Wed, 6 Feb 2019 04:41:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1549428078; bh=/VHxJyIBpRzCH+yqtI/5Hc0l7YU9N4pdah5ExIwuEy0=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=kJcTv9tl7kedIqQ7s/q6H0aaFwvnqvWgLC0F0CiMidsFQ8aLBdJ7aIYSnDnJQ0YxQ 464KAtKWRM+LYt6tH0OEE3CAQMAY13H9wXOlXGRtyJULC8/OBel7jQCnahKNSVTMHH GxGZqXsxIZuaALjfYBIlTyqna+DLsy42viuHnOUU= Date: Wed, 6 Feb 2019 13:41:15 +0900 From: Masami Hiramatsu To: Kees Cook Cc: Mathieu Desnoyers , William Cohen , "# 3.4.x" , Laura Abbott , Masami Hiramatsu , Russell King , linux-kernel , lttng@reliableembeddedsystems.com, lttng-dev Subject: Re: BUG: optimized kprobes illegal instructions in v4.19 stable kernels Message-Id: <20190206134115.baba291e33022a2f6b6ae5f8@kernel.org> In-Reply-To: References: <342740659.2887.1549307721609.JavaMail.zimbra@efficios.com> X-Mailer: Sylpheed 3.5.0 (GTK+ 2.24.30; 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 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 5 Feb 2019 15:06:10 +0000 Kees Cook wrote: > On Mon, Feb 4, 2019 at 7:15 PM Mathieu Desnoyers > wrote: > > > > Hi, > > > > I notice this commit as a possible culprit of the illegal instructions my lttng > > users are noticing on arm32 when using kprobes on a v4.19.13 Linux kernel > > in a Yocto environment [1]. They were able to reproduce the issue with perf > > as well. > > > > commit e46daee53bb50bde38805f1823a182979724c229 > > Author: Kees Cook > > Date: Tue Oct 30 22:12:56 2018 +0100 > > > > ARM: 8806/1: kprobes: Fix false positive with FORTIFY_SOURCE > > > > I *think* the intent there was to do > > > > - memcpy(code, &optprobe_template_entry, > > + memcpy(code, (unsigned long *)&optprobe_template_entry, > > > > But if you look at the commit, the "&" seems to have been stripped away, > > which happens to change the behavior significantly. > > Yeah, this was a typo on my part. :( Ah, I thought it had been fixed as same as x86. On x86, all optprobe_template_* are defined as kprobe_opcode_t [], but on arm, it still be kprobe_opcode_t. Hmm, but I think we should use kprobe_opcode_t [] or char[] as asm/sections.h does. OK, I'll prepare for the change. Thank you, > > > Has this change ever been runtime-tested ? > > I thought I had, given the details from the original bug report, but > clearly it didn't exercise it. > > Thanks for fixing this! > > -Kees > > > > > It has been backported to: > > - 4.19 stable as commit 3fe0c68aea21 > > - 4.14 stable as commit f9e0bc710347 > > > > Thanks, > > > > Mathieu > > > > [1] https://bugs.lttng.org/issues/1174 > > > > -- > > Mathieu Desnoyers > > EfficiOS Inc. > > http://www.efficios.com > > > > -- > Kees Cook -- Masami Hiramatsu