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=-7.5 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 60398C4649B for ; Fri, 5 Jul 2019 14:28:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 339752133F for ; Fri, 5 Jul 2019 14:28:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KoGYTwpg" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727757AbfGEO2S (ORCPT ); Fri, 5 Jul 2019 10:28:18 -0400 Received: from mail-io1-f68.google.com ([209.85.166.68]:39417 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725813AbfGEO2S (ORCPT ); Fri, 5 Jul 2019 10:28:18 -0400 Received: by mail-io1-f68.google.com with SMTP id f4so4009774ioh.6 for ; Fri, 05 Jul 2019 07:28:18 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=NPq0WihBXfIIIGpQocBmiVcY+JuiOESvD/Tk2IWEX/Q=; b=KoGYTwpgVjTXOCfpJyHC6rlkFPLQQ5lYJCzFURSIkpBuBrC4UWGTxex3Z/dFgzodeV QwWAaJPFDDm3BmNeVqr+9hrbt7rcTDNaSv/7iG2qSB4TO/U05aVgykxXl/Jrdv7kEilZ oVbr6rh21Ib8FQ/ioozI4k84tocKFwTIwss6XaHCHSH7zPMQWjOLqUcpTrcKIfT6guHR ZUROHzzCAtlEuKQl3LHxoJ7f6a2c22Ylsyfvvb8zBrR5VT/vGKlpQX7SDxAm5rmkvRQA tL1FV4FOcgd12IyZTxI30dMN9wz0wqrSg55BzE8XeF9X9ydtruFqC15Or9QqKMr22TkH O0QQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=NPq0WihBXfIIIGpQocBmiVcY+JuiOESvD/Tk2IWEX/Q=; b=KBP08g2qC4Ok45ESo24EmfVCFm86z/FfWHemi3FTAEkGLIds9wIHPsXZM7nI+d5HiN uU+93vjUMZyYPqoytnDoWUVOWYNVWuI4JsgWS81iBI4AMobUoCRYY8eS+/zmwPt+fzLS G2P12P98+D2/9DL6T2lmcuSPYdIIZrRTIdBYsyRiXHdIG02PRn6tdaNWxS2QZevS2eyi rgyELkNWYoxdKjlNHZObLw5AZo+8cYj++ovpEalMkFLbMYl79kPN3y8O3jCweqYmWrlh xYt2xzDnQV4sYGb5hWnsaezp25wGW6hez6mIcJxqEx6X+NtiBjEmwRRT3JODyHM/74xP PBtQ== X-Gm-Message-State: APjAAAVawJV2vLyVRQJda5GPHX9EWM2+CUxIsuAKk4X+DdyaXR+BkKSn 3c78urLUlmouKacR6PYkACo= X-Google-Smtp-Source: APXvYqxCb7bkI8IjcVj5Zzlsf2WT2qLLG9t+SCEtvpOESU9J1rXUhDjQ+2vZcRS7Gt6Q+btgkWefqw== X-Received: by 2002:a6b:bbc1:: with SMTP id l184mr4790320iof.232.1562336897861; Fri, 05 Jul 2019 07:28:17 -0700 (PDT) Received: from ?IPv6:2601:284:8200:5cfb:24ad:1b47:cd28:1699? ([2601:284:8200:5cfb:24ad:1b47:cd28:1699]) by smtp.googlemail.com with ESMTPSA id n21sm6263072ioh.30.2019.07.05.07.28.16 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 05 Jul 2019 07:28:16 -0700 (PDT) Subject: Re: NEIGH: BUG, double timer add, state is 8 To: Marek Majkowski , David Miller Cc: netdev@vger.kernel.org, kernel-team References: From: David Ahern Message-ID: <1f4be489-4369-01d1-41c6-1406006df9c5@gmail.com> Date: Fri, 5 Jul 2019 08:28:15 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 7/4/19 3:59 PM, Marek Majkowski wrote: > I found a way to hit an obscure BUG in the > net/core/neighbour.c:neigh_add_timer(), by piping two carefully > crafted messages into AF_NETLINK socket. > > https://github.com/torvalds/linux/blob/v5.2-rc7/net/core/neighbour.c#L259 > > if (unlikely(mod_timer(&n->timer, when))) { > printk("NEIGH: BUG, double timer add, state is %x\n", n->nud_state); > dump_stack(); > } > > The repro is here: > https://gist.github.com/majek/d70297b9d72bc2e2b82145e122722a0c > > wget https://gist.githubusercontent.com/majek/d70297b9d72bc2e2b82145e122722a0c/raw/9e140bcedecc28d722022f1da142a379a9b7a7b0/double_timer_add_bug.c Thanks for the report - and the reproducer. I am on PTO through Monday; I will take a look next week if no one else does.