From patchwork Mon Nov 9 12:55:32 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: 322580 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=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 6EEBDC388F7 for ; Mon, 9 Nov 2020 13:43:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 330A4206B2 for ; Mon, 9 Nov 2020 13:43:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604929417; bh=zI94Fjt1LxO8dQyFj8RFvyuAwoLB2+02+ybwG2pZAmw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=aMgX5Z0/jcjqOPopLq6ptCW1862Z523oWDdlCJG/NrSU6IECpV4WnlMaSpjw4CKuP 9jmCjPu8j/Tr2Yz4F69597dMJWOhrnWEmXX1vOl9HTX9xHIhNYIfQkB8vD46E1TthF K7nRI+eZCM/mcRTys21UW3kkUiIx3wMn/GwtjuOM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730403AbgKINng (ORCPT ); Mon, 9 Nov 2020 08:43:36 -0500 Received: from mail.kernel.org ([198.145.29.99]:54088 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730408AbgKIM7y (ORCPT ); Mon, 9 Nov 2020 07:59:54 -0500 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 5AF8C20789; Mon, 9 Nov 2020 12:59:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604926794; bh=zI94Fjt1LxO8dQyFj8RFvyuAwoLB2+02+ybwG2pZAmw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kb4PBHxkPyLh0k+ikizURkea1BZ2dAjq/AKY+o7B2KqHZuU3OkNdIbPu2+tYjBNcj UsGkV4oz1pZb2cQtdy/7ZJHrRVWGsL4UzdYmJ4/LJrjBMouLqHf/uODlWLLKdvF7Hf J3qOLOrTWW8KylsJeoh623oWO+v8dWwSBCqp7JTY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vineet Gupta Subject: [PATCH 4.4 85/86] ARC: stack unwinding: avoid indefinite looping Date: Mon, 9 Nov 2020 13:55:32 +0100 Message-Id: <20201109125024.873064392@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125020.852643676@linuxfoundation.org> References: <20201109125020.852643676@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Vineet Gupta commit 328d2168ca524d501fc4b133d6be076142bd305c upstream. Currently stack unwinder is a while(1) loop which relies on the dwarf unwinder to signal termination, which in turn relies on dwarf info to do so. This in theory could cause an infinite loop if the dwarf info was somehow messed up or the register contents were etc. This fix thus detects the excessive looping and breaks the loop. | Mem: 26184K used, 1009136K free, 0K shrd, 0K buff, 14416K cached | CPU: 0.0% usr 72.8% sys 0.0% nic 27.1% idle 0.0% io 0.0% irq 0.0% sirq | Load average: 4.33 2.60 1.11 2/74 139 | PID PPID USER STAT VSZ %VSZ CPU %CPU COMMAND | 133 2 root SWN 0 0.0 3 22.9 [rcu_torture_rea] | 132 2 root SWN 0 0.0 0 22.0 [rcu_torture_rea] | 131 2 root SWN 0 0.0 3 21.5 [rcu_torture_rea] | 126 2 root RW 0 0.0 2 5.4 [rcu_torture_wri] | 129 2 root SWN 0 0.0 0 0.2 [rcu_torture_fak] | 137 2 root SW 0 0.0 0 0.2 [rcu_torture_cbf] | 127 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 138 115 root R 1464 0.1 2 0.1 top | 130 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 128 2 root SWN 0 0.0 0 0.1 [rcu_torture_fak] | 115 1 root S 1472 0.1 1 0.0 -/bin/sh | 104 1 root S 1464 0.1 0 0.0 inetd | 1 0 root S 1456 0.1 2 0.0 init | 78 1 root S 1456 0.1 0 0.0 syslogd -O /var/log/messages | 134 2 root SW 0 0.0 2 0.0 [rcu_torture_sta] | 10 2 root IW 0 0.0 1 0.0 [rcu_preempt] | 88 2 root IW 0 0.0 1 0.0 [kworker/1:1-eve] | 66 2 root IW 0 0.0 2 0.0 [kworker/2:2-eve] | 39 2 root IW 0 0.0 2 0.0 [kworker/2:1-eve] | unwinder looping too long, aborting ! Cc: Signed-off-by: Vineet Gupta Signed-off-by: Greg Kroah-Hartman --- arch/arc/kernel/stacktrace.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/arch/arc/kernel/stacktrace.c +++ b/arch/arc/kernel/stacktrace.c @@ -113,7 +113,7 @@ arc_unwind_core(struct task_struct *tsk, int (*consumer_fn) (unsigned int, void *), void *arg) { #ifdef CONFIG_ARC_DW2_UNWIND - int ret = 0; + int ret = 0, cnt = 0; unsigned int address; struct unwind_frame_info frame_info; @@ -133,6 +133,11 @@ arc_unwind_core(struct task_struct *tsk, break; frame_info.regs.r63 = frame_info.regs.r31; + + if (cnt++ > 128) { + printk("unwinder looping too long, aborting !\n"); + return 0; + } } return address; /* return the last address it saw */