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=-2.6 required=3.0 tests=DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, 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 EC753C433F5 for ; Wed, 5 Sep 2018 10:46:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 25EE920658 for ; Wed, 5 Sep 2018 10:46:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=aepfle.de header.i=@aepfle.de header.b="Ul6KwiIL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 25EE920658 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=aepfle.de Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727713AbeIEPQg (ORCPT ); Wed, 5 Sep 2018 11:16:36 -0400 Received: from mo4-p00-ob.smtp.rzone.de ([85.215.255.22]:15207 "EHLO mo4-p00-ob.smtp.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726035AbeIEPQg (ORCPT ); Wed, 5 Sep 2018 11:16:36 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; t=1536144414; s=strato-dkim-0002; d=aepfle.de; h=Message-Id:Date:Subject:Cc:To:From:X-RZG-CLASS-ID:X-RZG-AUTH:From: Subject:Sender; bh=lD/QF+OltCAkjExq/G0OCx963mHS5ZNz5g/y9D66RNQ=; b=Ul6KwiILbXiFXOKfk7yy3MobO8r/orz/ad7YOhYgmuCzJsSjEWuI7vRze/H27RJsEB T/Ud0gt7uWfmL2iAKcY71ecDjncl+WpHdrxZ9jYN4jqcVu/kb9+3HuhLSo/iZfiwgQ5a FUHA1H2iAgj1B4y/d1OFwozwxt4LayCfnx+HP056+ylbTJIOCHOAN0zax9v2334eE6zN 1phfuIdxFxHRdNLl/35L4fTluSXzjg2JgbqMI2TD1lD5h2v4PNzWQtQdptgpTwNVJOxp aktqPxn8suzbwKsvdpqNzx5JSFmYOBi3jILRt7k5RqCN8EF0vS/JpJbPrrxy3jGLyGeR X4/Q== X-RZG-AUTH: ":P2EQZWCpfu+qG7CngxMFH1J+3q8wa/QXkBR9MXjAuzpIG0mv9coXAgc0/lb4QMstw0mqi/C51hpW50R4vli8caicjAbM" X-RZG-CLASS-ID: mo00 Received: from sender by smtp.strato.de (RZmta 44.0 AUTH) with ESMTPSA id L0862bu85Aeg4nP (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (curve secp521r1 with 521 ECDH bits, eq. 15360 bits RSA)) (Client did not present a certificate); Wed, 5 Sep 2018 12:40:42 +0200 (CEST) From: Olaf Hering To: xen-devel@lists.xenproject.org Cc: Olaf Hering , Boris Ostrovsky , Juergen Gross , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v1] xen: avoid crash in disable_hotplug_cpu Date: Wed, 5 Sep 2018 12:40:39 +0200 Message-Id: <20180905104039.13512-1-olaf@aepfle.de> X-Mailer: git-send-email 2.16.4 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The command 'xl vcpu-set 0 0', issued in dom0, will crash dom0: BUG: unable to handle kernel NULL pointer dereference at 00000000000002d8 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 7 PID: 65 Comm: xenwatch Not tainted 4.19.0-rc2-1.ga9462db-default #1 openSUSE Tumbleweed (unreleased) Hardware name: Intel Corporation S5520UR/S5520UR, BIOS S5500.86B.01.00.0050.050620101605 05/06/2010 RIP: e030:device_offline+0x9/0xb0 Code: 77 24 00 e9 ce fe ff ff 48 8b 13 e9 68 ff ff ff 48 8b 13 e9 29 ff ff ff 48 8b 13 e9 ea fe ff ff 90 66 66 66 66 90 41 54 55 53 87 d8 02 00 00 01 0f 85 88 00 00 00 48 c7 c2 20 09 60 81 31 f6 RSP: e02b:ffffc90040f27e80 EFLAGS: 00010203 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff8801f3800000 RSI: ffffc90040f27e70 RDI: 0000000000000000 RBP: 0000000000000000 R08: ffffffff820e47b3 R09: 0000000000000000 R10: 0000000000007ff0 R11: 0000000000000000 R12: ffffffff822e6d30 R13: dead000000000200 R14: dead000000000100 R15: ffffffff8158b4e0 FS: 00007ffa595158c0(0000) GS:ffff8801f39c0000(0000) knlGS:0000000000000000 CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000000002d8 CR3: 00000001d9602000 CR4: 0000000000002660 Call Trace: handle_vcpu_hotplug_event+0xb5/0xc0 xenwatch_thread+0x80/0x140 ? wait_woken+0x80/0x80 kthread+0x112/0x130 ? kthread_create_worker_on_cpu+0x40/0x40 ret_from_fork+0x3a/0x50 Fix this crash by checking the return value of get_cpu_device(). Signed-off-by: Olaf Hering --- drivers/xen/cpu_hotplug.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/xen/cpu_hotplug.c b/drivers/xen/cpu_hotplug.c index d4265c8ebb22..182be49f5a0b 100644 --- a/drivers/xen/cpu_hotplug.c +++ b/drivers/xen/cpu_hotplug.c @@ -19,9 +19,13 @@ static void enable_hotplug_cpu(int cpu) static void disable_hotplug_cpu(int cpu) { + struct device *dev; + if (cpu_online(cpu)) { lock_device_hotplug(); - device_offline(get_cpu_device(cpu)); + dev = get_cpu_device(cpu); + if (dev) + device_offline(dev); unlock_device_hotplug(); } if (cpu_present(cpu))