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=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 EBC88CA9EA0 for ; Tue, 22 Oct 2019 08:58:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BC83820679 for ; Tue, 22 Oct 2019 08:58:49 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=jv-coder.de header.i=@jv-coder.de header.b="WaY/fLxd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731339AbfJVI6s (ORCPT ); Tue, 22 Oct 2019 04:58:48 -0400 Received: from mail.jv-coder.de ([5.9.79.73]:52360 "EHLO mail.jv-coder.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726978AbfJVI6s (ORCPT ); Tue, 22 Oct 2019 04:58:48 -0400 Received: from [10.61.40.7] (unknown [37.156.92.209]) by mail.jv-coder.de (Postfix) with ESMTPSA id 0B15E9FA2B; Tue, 22 Oct 2019 08:58:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=jv-coder.de; s=dkim; t=1571734725; bh=vmxqbKFdbAsB2xDI6xrGHn1DS1Pl2hjh1JTq6d0++zQ=; h=Subject:To:From:Message-ID:Date:MIME-Version; b=WaY/fLxdqDRfcENriUsOVoPh73icYTpF1VgO6o5bxJNM01aauwiOzp9lCRKS9B3vK 5KoM41PObQR9ArA1fz1xpvcODULVcq0k2kO+dCgfhyg/tn/I6z8j42wYJXewMet+GD O7u97x0Mvf0rZp/wHmFI3R5isw3GgWdM860/tAx8= Subject: Re: [PATCH] xfrm : lock input tasklet skb queue To: Tom Rix , steffen.klassert@secunet.com, herbert@gondor.apana.org.au, davem@davemloft.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Joerg Vehlow Message-ID: Date: Tue, 22 Oct 2019 10:58:44 +0200 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.1.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, I already send a patch on 2019-09-09 to this mailing list with a similar issue[1]. Sadly no replies, although this is a huge bug in the rt kernel. I fixed it a bit differently, using smaller locked regions. You have also propably a bug in your patch, because trans->queue.lock is no initialized by __skb_queue_head_init (in xfrm_input_init) Jörg [1] https://lkml.org/lkml/2019/9/9/111 Am 20.10.2019 um 17:46 schrieb Tom Rix: > On PREEMPT_RT_FULL while running netperf, a corruption > of the skb queue causes an oops. > > This appears to be caused by a race condition here > __skb_queue_tail(&trans->queue, skb); > tasklet_schedule(&trans->tasklet); > Where the queue is changed before the tasklet is locked by > tasklet_schedule. > > The fix is to use the skb queue lock. > > Signed-off-by: Tom Rix > --- > net/xfrm/xfrm_input.c | 11 ++++++++++- > 1 file changed, 10 insertions(+), 1 deletion(-) > > diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c > index 9b599ed66d97..226dead86828 100644 > --- a/net/xfrm/xfrm_input.c > +++ b/net/xfrm/xfrm_input.c > @@ -758,12 +758,16 @@ static void xfrm_trans_reinject(unsigned long data) > struct xfrm_trans_tasklet *trans = (void *)data; > struct sk_buff_head queue; > struct sk_buff *skb; > + unsigned long flags; > > __skb_queue_head_init(&queue); > + spin_lock_irqsave(&trans->queue.lock, flags); > skb_queue_splice_init(&trans->queue, &queue); > > while ((skb = __skb_dequeue(&queue))) > XFRM_TRANS_SKB_CB(skb)->finish(dev_net(skb->dev), NULL, skb); > + > + spin_unlock_irqrestore(&trans->queue.lock, flags); > } > > int xfrm_trans_queue(struct sk_buff *skb, > @@ -771,15 +775,20 @@ int xfrm_trans_queue(struct sk_buff *skb, > struct sk_buff *)) > { > struct xfrm_trans_tasklet *trans; > + unsigned long flags; > > trans = this_cpu_ptr(&xfrm_trans_tasklet); > + spin_lock_irqsave(&trans->queue.lock, flags); > > - if (skb_queue_len(&trans->queue) >= netdev_max_backlog) > + if (skb_queue_len(&trans->queue) >= netdev_max_backlog) { > + spin_unlock_irqrestore(&trans->queue.lock, flags); > return -ENOBUFS; > + } > > XFRM_TRANS_SKB_CB(skb)->finish = finish; > __skb_queue_tail(&trans->queue, skb); > tasklet_schedule(&trans->tasklet); > + spin_unlock_irqrestore(&trans->queue.lock, flags); > return 0; > } > EXPORT_SYMBOL(xfrm_trans_queue);