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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,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 EA8C0C606BD for ; Mon, 8 Jul 2019 17:50:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C44152189F for ; Mon, 8 Jul 2019 17:50:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="OZ5opmc6" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404066AbfGHRu1 (ORCPT ); Mon, 8 Jul 2019 13:50:27 -0400 Received: from mail-qt1-f196.google.com ([209.85.160.196]:35210 "EHLO mail-qt1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729038AbfGHRu1 (ORCPT ); Mon, 8 Jul 2019 13:50:27 -0400 Received: by mail-qt1-f196.google.com with SMTP id d23so18940570qto.2 for ; Mon, 08 Jul 2019 10:50:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=yL5BRmtaPbPkgux2h8HVt6KP5oApfrPeQ3tBLfzIdSU=; b=OZ5opmc6L7elFVmJBDlWcGFG6GY0fE1yQP+zwuSbeqLjB1kHLXdsmV8DcALWFrfzzQ hdQgY1/aHqJ5eESq5nOmZC2NjQ07Lc56IqoVFws+4z3rCrCC2ihceYwIR4FepwxfO9+H xdq3qtqBwjGp+/Hwrzn4UKWeJ+zwS3cN8dQyU8r3s1f3bAzUX/yOahA1k7dsezmxitjY 8co8wChHtFo1MwvxewyiQyjGGpUuRgXO5yt7kSv0D8i8YDJtY6Tk2nJxBQK7N1G8EfjI sOR0uH6Bs192pfn6afB1ikq2npEt3ts7J1TovO03hujpILG51zqoSlyY/ox8tCW2QUhm a5sA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=yL5BRmtaPbPkgux2h8HVt6KP5oApfrPeQ3tBLfzIdSU=; b=g5+/16gRugCY8C6G6jKkPnJHj6F1Vh5rSCYKvTE3QTlwPDy85eVZ3lLTej/x9obMIN zuahen1z2Jkf7ltESgCCtcDw2WoKy2g5QEPXLeLArkS+j6ZR+bXI4ok7uYAzNQspbbvD pId4IwlWCW5HdgcNnad4v8U8TzASaW4bEtdkAttWYJIZEmx0DbhdvA2oAJX/DndDC60Z tCEbs7V4GRvBv3NNScW93KKxTOYLlN289/xaGPO4795oiICAQttusRTVfTZDMdw9oPqZ 5oYtShrGvyJ3ia5gxV/hVxCBFb1ioMGOqLYUD2wqv3E+oK+zbVpEaPCATMj6ihN5iGcP yMDg== X-Gm-Message-State: APjAAAW6SkIdEh2CM6KI9a09sUqrYyGujTrNniIiAGCO0CswN64U1y3m +DTzGdf08zy3jX2MtMmFnURBLHJ5CHTMLg== X-Google-Smtp-Source: APXvYqzyRwj+FvFh3OAmcgN2w65t+gP7/eJLQtjFQNIbuzr4Uzj62KUE+402oSxbzV2SqfCGQ1kPgA== X-Received: by 2002:ac8:c0e:: with SMTP id k14mr15091775qti.72.1562608226174; Mon, 08 Jul 2019 10:50:26 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-156-34-55-100.dhcp-dynamic.fibreop.ns.bellaliant.net. [156.34.55.100]) by smtp.gmail.com with ESMTPSA id p4sm8298394qkb.84.2019.07.08.10.50.25 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 08 Jul 2019 10:50:25 -0700 (PDT) Received: from jgg by mlx.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hkXmT-0001pJ-Ca; Mon, 08 Jul 2019 14:50:25 -0300 Date: Mon, 8 Jul 2019 14:50:25 -0300 From: Jason Gunthorpe To: Dag Moxnes Cc: dledford@redhat.com, leon@kernel.org, parav@mellanox.com, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] RDMA/core: Fix race when resolving IP address Message-ID: <20190708175025.GA6976@ziepe.ca> References: <1562584584-13132-1-git-send-email-dag.moxnes@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1562584584-13132-1-git-send-email-dag.moxnes@oracle.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 08, 2019 at 01:16:24PM +0200, Dag Moxnes wrote: > Use neighbour lock when copying MAC address from neighbour data struct > in dst_fetch_ha. > > When not using the lock, it is possible for the function to race with > neigh_update, causing it to copy an invalid MAC address. > > It is possible to provoke this error by calling rdma_resolve_addr in a > tight loop, while deleting the corresponding ARP entry in another tight > loop. > > This will cause the race shown it the following sample trace: > > rdma_resolve_addr() > rdma_resolve_ip() > addr_resolve() > addr_resolve_neigh() > fetch_ha() > dst_fetch_ha() > n->nud_state == NUD_VALID It isn't nud_state that is the problem here, it is the parallel memcpy's onto ha. I fixed the commit message This could also have been solved by using the ha_lock, but I don't think we have a reason to particularly over-optimize this. > drivers/infiniband/core/addr.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) Applied to for-next, thanks Jason