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 autolearn=unavailable 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 694F6C43381 for ; Tue, 26 Feb 2019 01:36:12 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 34E342184D for ; Tue, 26 Feb 2019 01:36:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551144972; bh=6DcnrVghzZeTUybLqN1CTvs941b+DR8H4duXbM6skL4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:List-ID:From; b=dWC+EEkru45nfn5157ZxGbAWeOJZjplqwqq9+MWwW5YCQpYqgld8ZOyLpwNKQP3ts x9g/fg7kRppGMZB/Md7TrY+bztQsNIpry58QMCCADZHPqM8jH/ShLFH+WzB+YH9j3H s1MSM+vB/05SwKyoQQD6e/O2t5HmadrX4yFpytp0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726017AbfBZBgD (ORCPT ); Mon, 25 Feb 2019 20:36:03 -0500 Received: from mail.kernel.org ([198.145.29.99]:38150 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725842AbfBZBgC (ORCPT ); Mon, 25 Feb 2019 20:36:02 -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 6C878217F4; Tue, 26 Feb 2019 01:36:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1551144961; bh=6DcnrVghzZeTUybLqN1CTvs941b+DR8H4duXbM6skL4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=AqR5fd0XNuGwc7qwPKs4qZS6nlkOZpTIxsoFYLIaU15o2KD3Z7ziGitcQRtTmB/Uc r7P2XOQuSllDJWBlaXzDaVtYvJQDMEHn7//oXOwtq5fg3HBV2hOJv7rSoqZM5DAkgx yEBTaCvULPlcOG+PGfKjxe6Kw09fXPvuUJD1zCmE= Date: Tue, 26 Feb 2019 10:35:58 +0900 From: Masami Hiramatsu To: Steven Rostedt Cc: Andy Lutomirski , Linus Torvalds , Linux List Kernel Mailing , Ingo Molnar , Andrew Morton , stable , Changbin Du , Jann Horn , Kees Cook , Peter Zijlstra Subject: Re: [PATCH 1/2 v2] kprobe: Do not use uaccess functions to access kernel memory that can fault Message-Id: <20190226103558.db7c6b472fccad6e4bca8f56@kernel.org> In-Reply-To: <20190225114018.4d6b17d4@vmware.local.home> References: <20190215174712.372898450@goodmis.org> <20190219140330.5dd9e876@gandalf.local.home> <20190220171019.5e81a4946b56982f324f7c45@kernel.org> <20190220094926.0ab575b3@gandalf.local.home> <20190222172745.2c7205d62003c0a858e33278@kernel.org> <20190222173509.88489b7c5d1bf0e2ec2382ee@kernel.org> <20190223124746.d021973004c7c892c3b3fde1@kernel.org> <20190223194421.725a03fd@oasis.local.home> <20190225001757.519f40cd088c05fdd00a9397@kernel.org> <20190225114025.902c9031075e2f1fc55369a3@kernel.org> <20190225170945.d808659362b364298c3206e9@kernel.org> <20190225114018.4d6b17d4@vmware.local.home> 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 Mon, 25 Feb 2019 11:40:18 -0500 Steven Rostedt wrote: > On Mon, 25 Feb 2019 17:09:45 +0900 > Masami Hiramatsu wrote: > > > > This should probably go with whatever effort makes nmi_uaccess_ok() > > > available on all architectures. That being said, how about just > > > making copy_from_user_nmi() work on all architectures, even if it just > > > fails unconditionally on some of them? > > > > I think even if we have copy_from_user_nmi(), we need something like > > nmi_uaccess_ok() because without it we can not correctly use > > __copy_from_user_inatomic()... > > But wouldn't that just be part of the implementation of > "copy_from_user_nmi()" as being in an NMI just assumes being inatomic? Yes for copy_from_user_nmi(). But there are some other fundamental functions, like __get_user(). And when we optimize the loop in strncpy/strnlen from user in atomic, I think one nmi_access_ok() at entry is enough. Thank you, -- Masami Hiramatsu