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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 200BAC63777 for ; Mon, 16 Nov 2020 23:38:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A11A424198 for ; Mon, 16 Nov 2020 23:38:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="CK1aV41u"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="SorRIQfC" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730068AbgKPXiC (ORCPT ); Mon, 16 Nov 2020 18:38:02 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45800 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726844AbgKPXiC (ORCPT ); Mon, 16 Nov 2020 18:38:02 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 37B00C0613D2 for ; Mon, 16 Nov 2020 15:38:02 -0800 (PST) From: Thomas Gleixner DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1605569878; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=8OefT95E+juRmGEV5SggOLfq6zFjKC+jmvYROztnl1c=; b=CK1aV41u6ajjJ5Jx7htyBJ8AFtFRYFX1EJB3L+tCBkgfblOTLIFeU+ijxKh2hWYyh4X44/ 4gBEdtIL0bn61o2K3D22tf4dwkk6VCjpUorz/bpgKjf6KimmJjRkWBv619uBFC17VMBfp4 D1MXEZ+woHLKOx8rYP+5ly7571c0yGkCVfA+hTranmfxfLMVKfyVZjNzi6suyIb/Mv8KnF YOSr04AavSRS3xZIk4ndgiAnpMyRcwV/e6vUb37EhVcrDFJypC//Q6yCy3ShPMDIbJhwPL M/gxoR22TFGZR11MuIVT4m1V6jhtfBpdK58lmF/pvINvQeH+V2Y9+CITykdx/A== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1605569878; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=8OefT95E+juRmGEV5SggOLfq6zFjKC+jmvYROztnl1c=; b=SorRIQfCDbuLskoZtgFCU/9PyP4zUUadxNeIhtkSZOsN4P/eAMzTysGD0H6FpdMaEkhgHc 3YXVBr64OGg9fcDQ== To: Andy Lutomirski Cc: Borislav Petkov , Oleg Nesterov , Mark Mossberg , Ingo Molnar , X86 ML , LKML , "H. Peter Anvin" , Jann Horn , kyin@redhat.com Subject: Re: [PATCH v2] x86/dumpstack: Fix misleading instruction pointer error message In-Reply-To: References: <20201002042915.403558-1-mark.mossberg@gmail.com> <20201103125034.GA30391@redhat.com> <20201103171537.GC4111@zn.tnic> <20201103174744.GB23992@redhat.com> <20201103175237.GD4111@zn.tnic> <20201103181114.GC23992@redhat.com> <20201103182018.GE4111@zn.tnic> <87blfxx8ps.fsf@nanos.tec.linutronix.de> Date: Tue, 17 Nov 2020 00:37:58 +0100 Message-ID: <878sb0yisp.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Nov 16 2020 at 15:04, Andy Lutomirski wrote: > On Mon, Nov 16, 2020 at 2:01 PM Thomas Gleixner wrote: >> arch/x86/kernel/dumpstack.c | 23 +++++++++++++++++++---- >> 1 file changed, 19 insertions(+), 4 deletions(-) >> >> --- a/arch/x86/kernel/dumpstack.c >> +++ b/arch/x86/kernel/dumpstack.c >> @@ -78,6 +78,9 @@ static int copy_code(struct pt_regs *reg >> if (!user_mode(regs)) >> return copy_from_kernel_nofault(buf, (u8 *)src, nbytes); >> >> + /* The user space code from other tasks cannot be accessed. */ >> + if (regs != task_pt_regs(current)) >> + return -EPERM; > > Depending on exactly where this gets called, this may not be > sufficient. You should also check nmi_uaccess_okay(). which is what copy_from_user_nmi() already does.