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=-5.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 6EDCCC76191 for ; Thu, 18 Jul 2019 08:58:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3985A2173E for ; Thu, 18 Jul 2019 08:58:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="Sl/xHuoE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389566AbfGRI6g (ORCPT ); Thu, 18 Jul 2019 04:58:36 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:51220 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726383AbfGRI6f (ORCPT ); Thu, 18 Jul 2019 04:58:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=59pNHHpCEcKGOhsQiGgUt+ozL25ouhHhLVmOteYpHqo=; b=Sl/xHuoEHjnd9+oJnoOHl+/dV 503KCLncGOkHKgDtY+ZuvmefhEkKqCy1i7V2t9gROCg3zRoqmiR6Js9X0oD8qy3Y7Tth3LbmafYDT He1JTC/E5qR+RDoonXOpEFSw77sgdWgaesPD6TPI8NkcWwHiHUWsW7y5WDwGpt9EIcbYFmVBdu2FA bhUj3ItAO0m80sPA0kDGIVhNtMxtzHiIe4CYM9FFlyPbHb1ilO60jm++5uhJyrN/R/J2hnWh4aq+0 UmsbRbYswE7+2mTN0mguwwNsaNhIAdRhfIn107Cdwjmc7MLSSMBcKdut3FKmazKei3cL/6ohIy70T /uhe4BojQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1ho2Ee-00071l-H2; Thu, 18 Jul 2019 08:58:03 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 63545202173EA; Thu, 18 Jul 2019 10:57:54 +0200 (CEST) Date: Thu, 18 Jul 2019 10:57:54 +0200 From: Peter Zijlstra To: Vegard Nossum Cc: tglx@linutronix.de, bp@alien8.de, mingo@kernel.org, rostedt@goodmis.org, luto@kernel.org, torvalds@linux-foundation.org, hpa@zytor.com, dave.hansen@linux.intel.com, jgross@suse.com, linux-kernel@vger.kernel.org, zhe.he@windriver.com, joel@joelfernandes.org, devel@etsukata.com Subject: [PATCH] stacktrace: Force USER_DS for stack_trace_save_user() Message-ID: <20190718085754.GM3402@hirez.programming.kicks-ass.net> References: <20190711114054.406765395@infradead.org> <4c71e14d-3a32-c3bb-8e3b-6e5100853192@oracle.com> <20190717080725.GK3402@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 17, 2019 at 10:09:45AM +0200, Vegard Nossum wrote: > On 7/17/19 10:07 AM, Peter Zijlstra wrote: > > Does something like the below help? > Yes. Thanks! --- Subject: stacktrace: Force USER_DS for stack_trace_save_user() From: Peter Zijlstra Date: Thu Jul 18 10:47:47 CEST 2019 When walking userspace stacks, we should set USER_DS, otherwise access_ok() will not function as expected. Reported-by: Vegard Nossum Tested-by: Vegard Nossum Reported-by: Eiichi Tsukata Signed-off-by: Peter Zijlstra (Intel) --- --- a/kernel/stacktrace.c +++ b/kernel/stacktrace.c @@ -226,12 +226,17 @@ unsigned int stack_trace_save_user(unsig .store = store, .size = size, }; + mm_segment_t fs; /* Trace user stack if not a kernel thread */ if (current->flags & PF_KTHREAD) return 0; + fs = get_fs(); + set_fs(USER_DS); arch_stack_walk_user(consume_entry, &c, task_pt_regs(current)); + set_fs(fs); + return c.len; } #endif