From patchwork Mon Aug 3 12:19:42 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 266833 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=-13.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED, USER_AGENT_GIT 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 69193C433E0 for ; Mon, 3 Aug 2020 12:43:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38CB92054F for ; Mon, 3 Aug 2020 12:43:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596458606; bh=h5rqxxYfACI8lziQ7XNfbCk2S/drUfGwBebl1x248LA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=WfDQvAUXjMu9UTuwBY6PLVZ+sSP9QRQIb24WvfH7Vr2l3OFXB980AzgfqLr3P302r tT/OSzvIQKWEZ3Q+IVhZ4+EhvObCVucad0axiCtKNGB//XyBgI6U4v5s8cnrVB8tZ7 2xGXdvVgCwhbrX/gtqO/Exy2AuTPzVOhPFwlsUa0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728467AbgHCMaM (ORCPT ); Mon, 3 Aug 2020 08:30:12 -0400 Received: from mail.kernel.org ([198.145.29.99]:57052 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727006AbgHCMaI (ORCPT ); Mon, 3 Aug 2020 08:30:08 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 810AB208B3; Mon, 3 Aug 2020 12:30:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596457807; bh=h5rqxxYfACI8lziQ7XNfbCk2S/drUfGwBebl1x248LA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rFHNAq7fZC8tOMkPFfgNll1+OjU86hfmNqduZcxakraZfmUQBAnA4fbJQSnUgBKGv kgn9yKS2G1CAauy18odK7nx451XOiQrb32JX3/pzDZqMXmI8ICFegSIVF0oYAYu01s ZlZbUpwcXiCueoXIG9C+SLibieTqb0OTG08MHHD4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Wang ShaoBo , Josh Poimboeuf , Thomas Gleixner , Sasha Levin Subject: [PATCH 5.4 80/90] x86/stacktrace: Fix reliable check for empty user task stacks Date: Mon, 3 Aug 2020 14:19:42 +0200 Message-Id: <20200803121901.482736973@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200803121857.546052424@linuxfoundation.org> References: <20200803121857.546052424@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Josh Poimboeuf [ Upstream commit 039a7a30ec102ec866d382a66f87f6f7654f8140 ] If a user task's stack is empty, or if it only has user regs, ORC reports it as a reliable empty stack. But arch_stack_walk_reliable() incorrectly treats it as unreliable. That happens because the only success path for user tasks is inside the loop, which only iterates on non-empty stacks. Generally, a user task must end in a user regs frame, but an empty stack is an exception to that rule. Thanks to commit 71c95825289f ("x86/unwind/orc: Fix error handling in __unwind_start()"), unwind_start() now sets state->error appropriately. So now for both ORC and FP unwinders, unwind_done() and !unwind_error() always means the end of the stack was successfully reached. So the success path for kthreads is no longer needed -- it can also be used for empty user tasks. Reported-by: Wang ShaoBo Signed-off-by: Josh Poimboeuf Signed-off-by: Thomas Gleixner Tested-by: Wang ShaoBo Link: https://lkml.kernel.org/r/f136a4e5f019219cbc4f4da33b30c2f44fa65b84.1594994374.git.jpoimboe@redhat.com Signed-off-by: Sasha Levin --- arch/x86/kernel/stacktrace.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/arch/x86/kernel/stacktrace.c b/arch/x86/kernel/stacktrace.c index 2d6898c2cb647..6d83b4b857e6a 100644 --- a/arch/x86/kernel/stacktrace.c +++ b/arch/x86/kernel/stacktrace.c @@ -58,7 +58,6 @@ int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, * or a page fault), which can make frame pointers * unreliable. */ - if (IS_ENABLED(CONFIG_FRAME_POINTER)) return -EINVAL; } @@ -81,10 +80,6 @@ int arch_stack_walk_reliable(stack_trace_consume_fn consume_entry, if (unwind_error(&state)) return -EINVAL; - /* Success path for non-user tasks, i.e. kthreads and idle tasks */ - if (!(task->flags & (PF_KTHREAD | PF_IDLE))) - return -EINVAL; - return 0; }