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,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, 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 08411C43462 for ; Wed, 12 May 2021 16:37:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BB53261006 for ; Wed, 12 May 2021 16:37:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242714AbhELQfb (ORCPT ); Wed, 12 May 2021 12:35:31 -0400 Received: from mail.kernel.org ([198.145.29.99]:41730 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234150AbhELPnN (ORCPT ); Wed, 12 May 2021 11:43:13 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 782C861C87; Wed, 12 May 2021 15:22:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620832940; bh=B8iCQtKl6f99ZMNU0dijVVsCODS4TsCPh+5smRLGkZU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=daQ9HbQ/HDNiW/wo/PURogG5YcdOCMr/jzQcKUDgeG5EWb34a1vER5nUxTRBY69mZ S9UqhOHKWVRt2ju5+XuQ83rypxksuytySBLFNEf+bpW34iFDeejmp7ln5BNW6JmMDU iN8uXDlRFo3xdrTl6FMoXk2lJvFL4tSY2A4NSDjc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , "Gong, Sishuai" , Willem de Bruijn , "David S. Miller" , Sasha Levin Subject: [PATCH 5.10 449/530] net/packet: remove data races in fanout operations Date: Wed, 12 May 2021 16:49:19 +0200 Message-Id: <20210512144834.523524937@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144819.664462530@linuxfoundation.org> References: <20210512144819.664462530@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet [ Upstream commit 94f633ea8ade8418634d152ad0931133338226f6 ] af_packet fanout uses RCU rules to ensure f->arr elements are not dismantled before RCU grace period. However, it lacks rcu accessors to make sure KCSAN and other tools wont detect data races. Stupid compilers could also play games. Fixes: dc99f600698d ("packet: Add fanout support.") Signed-off-by: Eric Dumazet Reported-by: "Gong, Sishuai" Cc: Willem de Bruijn Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- net/packet/af_packet.c | 15 +++++++++------ net/packet/internal.h | 2 +- 2 files changed, 10 insertions(+), 7 deletions(-) diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 92501e5f9d49..449625c2ccc7 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -1358,7 +1358,7 @@ static unsigned int fanout_demux_rollover(struct packet_fanout *f, struct packet_sock *po, *po_next, *po_skip = NULL; unsigned int i, j, room = ROOM_NONE; - po = pkt_sk(f->arr[idx]); + po = pkt_sk(rcu_dereference(f->arr[idx])); if (try_self) { room = packet_rcv_has_room(po, skb); @@ -1370,7 +1370,7 @@ static unsigned int fanout_demux_rollover(struct packet_fanout *f, i = j = min_t(int, po->rollover->sock, num - 1); do { - po_next = pkt_sk(f->arr[i]); + po_next = pkt_sk(rcu_dereference(f->arr[i])); if (po_next != po_skip && !READ_ONCE(po_next->pressure) && packet_rcv_has_room(po_next, skb) == ROOM_NORMAL) { if (i != j) @@ -1465,7 +1465,7 @@ static int packet_rcv_fanout(struct sk_buff *skb, struct net_device *dev, if (fanout_has_flag(f, PACKET_FANOUT_FLAG_ROLLOVER)) idx = fanout_demux_rollover(f, skb, idx, true, num); - po = pkt_sk(f->arr[idx]); + po = pkt_sk(rcu_dereference(f->arr[idx])); return po->prot_hook.func(skb, dev, &po->prot_hook, orig_dev); } @@ -1479,7 +1479,7 @@ static void __fanout_link(struct sock *sk, struct packet_sock *po) struct packet_fanout *f = po->fanout; spin_lock(&f->lock); - f->arr[f->num_members] = sk; + rcu_assign_pointer(f->arr[f->num_members], sk); smp_wmb(); f->num_members++; if (f->num_members == 1) @@ -1494,11 +1494,14 @@ static void __fanout_unlink(struct sock *sk, struct packet_sock *po) spin_lock(&f->lock); for (i = 0; i < f->num_members; i++) { - if (f->arr[i] == sk) + if (rcu_dereference_protected(f->arr[i], + lockdep_is_held(&f->lock)) == sk) break; } BUG_ON(i >= f->num_members); - f->arr[i] = f->arr[f->num_members - 1]; + rcu_assign_pointer(f->arr[i], + rcu_dereference_protected(f->arr[f->num_members - 1], + lockdep_is_held(&f->lock))); f->num_members--; if (f->num_members == 0) __dev_remove_pack(&f->prot_hook); diff --git a/net/packet/internal.h b/net/packet/internal.h index baafc3f3fa25..7af1e9179385 100644 --- a/net/packet/internal.h +++ b/net/packet/internal.h @@ -94,7 +94,7 @@ struct packet_fanout { spinlock_t lock; refcount_t sk_ref; struct packet_type prot_hook ____cacheline_aligned_in_smp; - struct sock *arr[]; + struct sock __rcu *arr[]; }; struct packet_rollover { -- 2.30.2