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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 8160DC49EA2 for ; Mon, 21 Jun 2021 17:53:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 65245613B2 for ; Mon, 21 Jun 2021 17:53:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231760AbhFURze (ORCPT ); Mon, 21 Jun 2021 13:55:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:39086 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232109AbhFURyr (ORCPT ); Mon, 21 Jun 2021 13:54:47 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 2D6426134F; Mon, 21 Jun 2021 17:52:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624297950; bh=gdwqziYej5UQV+KrdT1l+V7grfC5iPSlLrDqLs8FbAY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tgMH0AyxXw2MXGTQ4+VAOV/5JQn81co8jdg4fp7uAE6CK4JiJdwFPmP+7WaheEfaL 35QRQQ1bo1XAQtmOEGVxgJJ34DEKUe5R1t/cpjDU2LZt/M1rDZA/vOZpCOrNBqTSzm NAUror4KdbODYbe0pzRUYEjaEsKONuv02BmiV3yggJhpIZgd7Efhr+cmnW4Hh6XivY skUH9u7S7hmkEdI4e0Hy2M9M+gaVv2C7AZ8vC/H5PLzybHvsgMqykBbpQ6gskgpklX AmrdtUaSNJKUFlIn29esLkr4v6Ns32ZMz3sX1MCnvbi49LQjZ0sTYFGEsaZzwFvdOF zf9jMsHK49aRg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Dumazet , "David S . Miller" , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 5.12 20/39] net/packet: annotate data race in packet_sendmsg() Date: Mon, 21 Jun 2021 13:51:36 -0400 Message-Id: <20210621175156.735062-20-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210621175156.735062-1-sashal@kernel.org> References: <20210621175156.735062-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet [ Upstream commit d1b5bee4c8be01585033be9b3a8878789285285f ] There is a known race in packet_sendmsg(), addressed in commit 32d3182cd2cd ("net/packet: fix race in tpacket_snd()") Now we have data_race(), we can use it to avoid a future KCSAN warning, as syzbot loves stressing af_packet sockets :) Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/packet/af_packet.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index c52557ec7fb3..84d8921391c3 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -3034,10 +3034,13 @@ static int packet_sendmsg(struct socket *sock, struct msghdr *msg, size_t len) struct sock *sk = sock->sk; struct packet_sock *po = pkt_sk(sk); - if (po->tx_ring.pg_vec) + /* Reading tx_ring.pg_vec without holding pg_vec_lock is racy. + * tpacket_snd() will redo the check safely. + */ + if (data_race(po->tx_ring.pg_vec)) return tpacket_snd(po, msg); - else - return packet_snd(sock, msg, len); + + return packet_snd(sock, msg, len); } /* -- 2.30.2