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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 044FFC433E0 for ; Tue, 30 Jun 2020 14:56:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D587520675 for ; Tue, 30 Jun 2020 14:56:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729260AbgF3O4j (ORCPT ); Tue, 30 Jun 2020 10:56:39 -0400 Received: from www62.your-server.de ([213.133.104.62]:37070 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728029AbgF3O4j (ORCPT ); Tue, 30 Jun 2020 10:56:39 -0400 Received: from sslproxy05.your-server.de ([78.46.172.2]) by www62.your-server.de with esmtpsa (TLSv1.2:DHE-RSA-AES256-GCM-SHA384:256) (Exim 4.89_1) (envelope-from ) id 1jqHgb-0005vi-Qz; Tue, 30 Jun 2020 16:56:37 +0200 Received: from [178.196.57.75] (helo=pc-9.home) by sslproxy05.your-server.de with esmtpsa (TLSv1.3:TLS_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1jqHgb-0004VV-Mf; Tue, 30 Jun 2020 16:56:37 +0200 Subject: Re: BUG: kernel NULL pointer dereference in __cgroup_bpf_run_filter_skb To: Rudi Ratloser , bpf@vger.kernel.org References: From: Daniel Borkmann Message-ID: Date: Tue, 30 Jun 2020 16:56:37 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Authenticated-Sender: daniel@iogearbox.net X-Virus-Scanned: Clear (ClamAV 0.102.3/25859/Tue Jun 30 15:38:05 2020) Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On 6/30/20 4:28 PM, Rudi Ratloser wrote: > We have experienced a kernel BPF null pointer dereference issue on all > our machines since mid of June. It might be related to an upgrade of > libvirt/kvm/qemu at that point of time. But we’re not sure. > > None of the servers can be used with this bug, as they crash latest > one hour after reboot. The time period until kernel panic can be > easily reduced down to 2 minutes, when starting one or more > applications of the following list: > - LXD daemon (4.2.1) > - libvirtd daemon (6.4.0) with qemu/kvm guests > - NFS server 2.5.1 > - Mozilla Firefox > - Mozilla Thunderbird > > If none of the applications run, the systems seem to be stable. > > Intermediate solution: > Downgrade Linux kernel to 4.9.226 LTS or 4.4.226 LTS on all the machines > > Why this solution works is not clear, yet. One of the major > differences we saw is, that both kernel packages have been configured > with user namespaces disabled. > > We experienced the kernel freeze on following Arch Linux kernels: > - 5.7.0 (5.7.0-3-MANJARO x64) > - 5.6.16 (5.6.16-1-MANJARO x64) > - 5.4.44 (5.4.44-1-MANJARO x64) > - 4.19.126 (4.19.126-1-MANJARO x64) > - 4.14.183 (4.14.183-1-MANJARO x64) > Kernel configs can be taken from https://gitlab.manjaro.org/packages/core. > > Subsequent e-mails will contain the relevant extracts from journal or > netconsole logs. > > Help and support on this issue is welcome. Fix is under discussion here: https://lore.kernel.org/netdev/20200616180352.18602-1-xiyou.wangcong@gmail.com/ Thanks, Daniel