From patchwork Mon Nov 9 12:55:54 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: 322639 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=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 64F26C4741F for ; Mon, 9 Nov 2020 13:32:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1BEAF2067B for ; Mon, 9 Nov 2020 13:32:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604928746; bh=HKtZLGfCgdWvCQ5U3VKuBC3uFGSb0cHEyo6P1ocRbho=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ccQRv3P6KWR5TgAfbneoPUreJrvjUdcBbSKkYsWwNiHZGI7c8q43pH3F2mpVkBgV5 Gk9BLy9MRdCwXCe4Cu2ngRDe5n5N/pPDgssEYuhkORaLX2uNPlGAOlxs2IDHU2XSI5 TYdjXWEG2bmr4BCvH1te4wjRSWFar20DZqMKo2Xs= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731343AbgKINHh (ORCPT ); Mon, 9 Nov 2020 08:07:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:60386 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731369AbgKINHe (ORCPT ); Mon, 9 Nov 2020 08:07:34 -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 9C07C20789; Mon, 9 Nov 2020 13:07:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604927253; bh=HKtZLGfCgdWvCQ5U3VKuBC3uFGSb0cHEyo6P1ocRbho=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NGWdSjOmO8b81ups2HFYyQHoXunUBtQnd9eRsKDRTIpzEgd5Qyf68nictl4f5+1jT cGbxZRDJV25J6YZWSdjnSUutjQSAc+1fjIX7+dmTDv1IfliTNNKMIz555hDa2S8Niw fjDhbv2rlyCaiFTLFP+LWQEFayurBEFMZQAczerY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Vineet Gupta Subject: [PATCH 4.14 45/48] ARC: stack unwinding: avoid indefinite looping Date: Mon, 9 Nov 2020 13:55:54 +0100 Message-Id: <20201109125018.978132382@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201109125016.734107741@linuxfoundation.org> References: <20201109125016.734107741@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 @@ -115,7 +115,7 @@ 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; @@ -135,6 +135,11 @@ 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 */