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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5B4ECCC6B34 for ; Thu, 15 Oct 2026 07:47:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Xj4hLpHjzheP4AEGLpAFn5JMjwlG+fQsoZ3qshX2rR0=; b=hK1m+Hozmli1Msq+H8+3GsNnG5 +axe+bYmeb61Ro/9xrZIgWo7WHOfuylehb2GMafingrYkRs0qZlyTKuljjySDeJ1Kv03RsIsWOolU VJclBj/X/XpqkxPieEX2z92S3a8lVA3UQKjKGigsICNH4Lnlddh/0jahVmi9RZAbRYy9uaTxzol+2 o1RwQ9V+DIh+8vYwlunBoyqrwtRI34Cx3RGjl/hOtKbKR73n32YmuUF+sQFHxZdIJtWjs9bxFnI9f TzBFEMGd0yNvV9jkliYUpH0z1LWggLB2MWcjbc4qKC62QZ/ky4sfB0A774RnGX9mhbnTOOsQmgbH9 d/MjAinA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1xHGB7-0000000H4JV-42iB; Thu, 15 Oct 2026 07:47:05 +0000 Received: from smtpout-03.galae.net ([185.246.85.4]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1xHGB4-0000000H4Gf-2jDM for linux-arm-kernel@lists.infradead.org; Thu, 15 Oct 2026 07:47:04 +0000 Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id B820F4E41246; Thu, 15 Oct 2026 07:46:56 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 73D0960360; Thu, 15 Oct 2026 07:46:56 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id B966010328B8D; Thu, 15 Oct 2026 09:46:42 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1792050414; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:content-language:in-reply-to:references; bh=Xj4hLpHjzheP4AEGLpAFn5JMjwlG+fQsoZ3qshX2rR0=; b=I4aZWQJa5eiMyD2REL02NTzzy7IuxQ8lj0letekuQ91rK5zrme4YUkJhRJysD+FfKkEYuT PEkt0FYKr1T6q2KU797FoRXLy7yRKSncC0itrLXXM3ogzKDH12QxTatZIPgFeiginCetqK wBObo6K1YafbwYlRDsar1dzlynLMsRa/2JFV3KWAYffJA0xLoLskd9OQ13dVitcYQcdL3k y+od1ZIbNhZcK8fkgkx1zCtPpem8AlyfVrri8SQRzW7d340wK5lXpTRlZWN2kjEBDHTFbc dgB9wfe1wfWQLBdqqk0XkA/thJiXwYCdxMwbOr9qZqyzH6zQEZl5PWG7/Tadsw== Message-ID: Date: Thu, 15 Oct 2026 09:46:41 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next 1/3] net: selftests: use skb_share_check() in the loopback receive hook To: Nicolai Buchwitz , netdev-bot+sashiko@kernel.org Cc: davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, horms@kernel.org, o.rempel@pengutronix.de, andrew+netdev@lunn.ch, mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com, Jose.Abreu@synopsys.com, saeedm@nvidia.com, tariqt@nvidia.com, mbloch@nvidia.com, leon@kernel.org, dtatulea@nvidia.com, alazar@nvidia.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-rdma@vger.kernel.org References: <20261007-nb-net-selftest-shared-net-v1-1-458369bfa1ba@tipi-net.de> <179149509090.434549.9918598206439291164@kernel.org> <533b88ce917b59f4f59f52145d2f035f@tipi-net.de> Content-Language: en-US From: Maxime Chevallier In-Reply-To: <533b88ce917b59f4f59f52145d2f035f@tipi-net.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Last-TLS-Session-Version: TLSv1.3 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261015_004702_837152_3A7A3D67 X-CRM114-Status: GOOD ( 10.08 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, On 10/9/26 08:49, Nicolai Buchwitz wrote: > Hi Clashiko > [...] >> >> Could an IPv4 frame that arrives during ethtool -t make the hook read up >> to about 64 bytes past skb->tail? Examples would be a minimum-size TCP >> segment or a frame with ihl=15. >> >> The over-read seems to stay inside the skb head allocation, because >> skb_shared_info follows skb->end. If so, the only effect is a possibly >> wrong selftest result. > > The length check is pre-existing, will address that in a follow-up patch. I'm unsure about this, Can we instead assume that when one is running the "ethtool -t" selftests on a machine, they are doing so in some controlled conditions ? IOW can we take the assumption that we won't get incoming traffic at the same time as we run the selftests, and if we do get some and that triggers a wrong result, this is expected ? ethtool selftests are very cheap to run, only a handful of seconds, and don't require any extra dependency, it doesn't cost much to re-run them if something unexpected happens during them. ofc. getting a stray frame during the selftests mustn't crash :) That's my take on these tests, but feel free to disagree :) Maxime