From patchwork Mon Aug 3 12:19:29 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 266808 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 48E8FC433E3 for ; Mon, 3 Aug 2020 12:47:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 250AC206D4 for ; Mon, 3 Aug 2020 12:47:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596458840; bh=k9WgX49UhER9eYl15sr7XTWMTSzUTaFe3tk7B9RNLmU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=i9UivQiymw0+Y9UEba8vpUFWEZn+rG/g/cuIaEXVH5HW6PKYZrapXw7gxLMuz+DIh PJdrnWMB5+LmvHiaPZAKjUdvGsCOuzAlDvQ6VofgED1xCXi19GUIoVhv+wtrE5qf+P zIcWxie48c3nuzYwQN2QmlHyO07UM5rxoQu8hpwU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728302AbgHCMZ5 (ORCPT ); Mon, 3 Aug 2020 08:25:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:51046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728296AbgHCMZ4 (ORCPT ); Mon, 3 Aug 2020 08:25:56 -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 143F0207DF; Mon, 3 Aug 2020 12:25:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596457555; bh=k9WgX49UhER9eYl15sr7XTWMTSzUTaFe3tk7B9RNLmU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=flgMXCEi80yhHssYGl3xQBRdhr7P/E6Kh0DcE5jnHAx7tDNasjumqOPMuYPtzoNDv 8z705IJ3DunxayIzdAxlfkgX2QG4/urgK2ed9ul90h3oM1tndt3jeYC41QoHokrep6 aviDcsQFGOMaU3bNgW9yo6TUhiw0E1NpOR7sMxdI= 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 5.7 111/120] x86/stacktrace: Fix reliable check for empty user task stacks Date: Mon, 3 Aug 2020 14:19:29 +0200 Message-Id: <20200803121908.300695312@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200803121902.860751811@linuxfoundation.org> References: <20200803121902.860751811@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 6ad43fc44556e..2fd698e28e4d5 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; }