From patchwork Tue Jan 7 20:55:36 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 234353 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=-9.8 required=3.0 tests=DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, 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 4B343C282DD for ; Tue, 7 Jan 2020 21:11:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 202862072A for ; Tue, 7 Jan 2020 21:11:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578431518; bh=Y5q8VHegwVHT2dXvZf2Mf+fu0BhmtH0aE8VudM/V+7g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Wuq/9/OAP1HKDjhblvZN2UHXgeu0CgZLWb4ben2H81TN3Om5APw0Xjjq8xfFyBSnZ X+IsLDiXjjr5gWMwB4xNJvp77NYF6bAEaD2LytJcfK/4bOh5+PlZgFnlRENpRSFLkV szFyciYuolSYylhloCSCQuhIheUDvrwBnz5pO5q0= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729979AbgAGVLi (ORCPT ); Tue, 7 Jan 2020 16:11:38 -0500 Received: from mail.kernel.org ([198.145.29.99]:40256 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729808AbgAGVLe (ORCPT ); Tue, 7 Jan 2020 16:11:34 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BDA1C2077B; Tue, 7 Jan 2020 21:11:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578431493; bh=Y5q8VHegwVHT2dXvZf2Mf+fu0BhmtH0aE8VudM/V+7g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=FelhNbghX7+rKJrq1k3GhOin+L5loM9n43ExVOIeQ+QIawdPSoCU8KIf+gXGNF/F+ 8VtMPrCAVQCceD8OjmFWBqwkNedzUzlGgS7fesJKdhB8CupC/SDhhhj6oIBgjugNe/ EZ3JrfMqFXJt1YGa/bY2SHtXMioijlnxuqoWOFio= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , syzbot , "David S. Miller" , Sasha Levin Subject: [PATCH 4.14 71/74] net: add annotations on hh->hh_len lockless accesses Date: Tue, 7 Jan 2020 21:55:36 +0100 Message-Id: <20200107205235.071680962@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200107205135.369001641@linuxfoundation.org> References: <20200107205135.369001641@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet [ Upstream commit c305c6ae79e2ce20c22660ceda94f0d86d639a82 ] KCSAN reported a data-race [1] While we can use READ_ONCE() on the read sides, we need to make sure hh->hh_len is written last. [1] BUG: KCSAN: data-race in eth_header_cache / neigh_resolve_output write to 0xffff8880b9dedcb8 of 4 bytes by task 29760 on cpu 0: eth_header_cache+0xa9/0xd0 net/ethernet/eth.c:247 neigh_hh_init net/core/neighbour.c:1463 [inline] neigh_resolve_output net/core/neighbour.c:1480 [inline] neigh_resolve_output+0x415/0x470 net/core/neighbour.c:1470 neigh_output include/net/neighbour.h:511 [inline] ip6_finish_output2+0x7a2/0xec0 net/ipv6/ip6_output.c:116 __ip6_finish_output net/ipv6/ip6_output.c:142 [inline] __ip6_finish_output+0x2d7/0x330 net/ipv6/ip6_output.c:127 ip6_finish_output+0x41/0x160 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip6_output+0xf2/0x280 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:436 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] ndisc_send_skb+0x459/0x5f0 net/ipv6/ndisc.c:505 ndisc_send_ns+0x207/0x430 net/ipv6/ndisc.c:647 rt6_probe_deferred+0x98/0xf0 net/ipv6/route.c:615 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 worker_thread+0xa0/0x800 kernel/workqueue.c:2415 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 read to 0xffff8880b9dedcb8 of 4 bytes by task 29572 on cpu 1: neigh_resolve_output net/core/neighbour.c:1479 [inline] neigh_resolve_output+0x113/0x470 net/core/neighbour.c:1470 neigh_output include/net/neighbour.h:511 [inline] ip6_finish_output2+0x7a2/0xec0 net/ipv6/ip6_output.c:116 __ip6_finish_output net/ipv6/ip6_output.c:142 [inline] __ip6_finish_output+0x2d7/0x330 net/ipv6/ip6_output.c:127 ip6_finish_output+0x41/0x160 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:294 [inline] ip6_output+0xf2/0x280 net/ipv6/ip6_output.c:175 dst_output include/net/dst.h:436 [inline] NF_HOOK include/linux/netfilter.h:305 [inline] ndisc_send_skb+0x459/0x5f0 net/ipv6/ndisc.c:505 ndisc_send_ns+0x207/0x430 net/ipv6/ndisc.c:647 rt6_probe_deferred+0x98/0xf0 net/ipv6/route.c:615 process_one_work+0x3d4/0x890 kernel/workqueue.c:2269 worker_thread+0xa0/0x800 kernel/workqueue.c:2415 kthread+0x1d4/0x200 drivers/block/aoe/aoecmd.c:1253 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:352 Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 29572 Comm: kworker/1:4 Not tainted 5.4.0-rc6+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events rt6_probe_deferred Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/firewire/net.c | 6 +++++- include/net/neighbour.h | 2 +- net/core/neighbour.c | 4 ++-- net/ethernet/eth.c | 7 ++++++- 4 files changed, 14 insertions(+), 5 deletions(-) diff --git a/drivers/firewire/net.c b/drivers/firewire/net.c index 242359c2d1f1..215f4f71b943 100644 --- a/drivers/firewire/net.c +++ b/drivers/firewire/net.c @@ -249,7 +249,11 @@ static int fwnet_header_cache(const struct neighbour *neigh, h = (struct fwnet_header *)((u8 *)hh->hh_data + HH_DATA_OFF(sizeof(*h))); h->h_proto = type; memcpy(h->h_dest, neigh->ha, net->addr_len); - hh->hh_len = FWNET_HLEN; + + /* Pairs with the READ_ONCE() in neigh_resolve_output(), + * neigh_hh_output() and neigh_update_hhs(). + */ + smp_store_release(&hh->hh_len, FWNET_HLEN); return 0; } diff --git a/include/net/neighbour.h b/include/net/neighbour.h index 1d6b98119a1d..e89273f9a0bc 100644 --- a/include/net/neighbour.h +++ b/include/net/neighbour.h @@ -458,7 +458,7 @@ static inline int neigh_hh_output(const struct hh_cache *hh, struct sk_buff *skb do { seq = read_seqbegin(&hh->hh_lock); - hh_len = hh->hh_len; + hh_len = READ_ONCE(hh->hh_len); if (likely(hh_len <= HH_DATA_MOD)) { hh_alen = HH_DATA_MOD; diff --git a/net/core/neighbour.c b/net/core/neighbour.c index 2664ad58e5c0..16ac50b1b9a7 100644 --- a/net/core/neighbour.c +++ b/net/core/neighbour.c @@ -1094,7 +1094,7 @@ static void neigh_update_hhs(struct neighbour *neigh) if (update) { hh = &neigh->hh; - if (hh->hh_len) { + if (READ_ONCE(hh->hh_len)) { write_seqlock_bh(&hh->hh_lock); update(hh, neigh->dev, neigh->ha); write_sequnlock_bh(&hh->hh_lock); @@ -1355,7 +1355,7 @@ int neigh_resolve_output(struct neighbour *neigh, struct sk_buff *skb) struct net_device *dev = neigh->dev; unsigned int seq; - if (dev->header_ops->cache && !neigh->hh.hh_len) + if (dev->header_ops->cache && !READ_ONCE(neigh->hh.hh_len)) neigh_hh_init(neigh); do { diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c index eaeba9b99a73..7e0e5f2706ba 100644 --- a/net/ethernet/eth.c +++ b/net/ethernet/eth.c @@ -239,7 +239,12 @@ int eth_header_cache(const struct neighbour *neigh, struct hh_cache *hh, __be16 eth->h_proto = type; memcpy(eth->h_source, dev->dev_addr, ETH_ALEN); memcpy(eth->h_dest, neigh->ha, ETH_ALEN); - hh->hh_len = ETH_HLEN; + + /* Pairs with READ_ONCE() in neigh_resolve_output(), + * neigh_hh_output() and neigh_update_hhs(). + */ + smp_store_release(&hh->hh_len, ETH_HLEN); + return 0; } EXPORT_SYMBOL(eth_header_cache);