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 C059FC4743C for ; Mon, 21 Jun 2021 18:10:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA8686100B for ; Mon, 21 Jun 2021 18:10:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233606AbhFUSMQ (ORCPT ); Mon, 21 Jun 2021 14:12:16 -0400 Received: from mail.kernel.org ([198.145.29.99]:47214 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234291AbhFUSFD (ORCPT ); Mon, 21 Jun 2021 14:05:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id A1A5861361; Mon, 21 Jun 2021 17:56:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624298174; bh=mmU/kR2om690Kl2wS4pMgv5x4TQtymKK0Qc78BQGgeI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=daJ3rOsbWuDml6H3AwjPPbceENNg2DxdVSVZY968di2xH20MOOko14BF0tXHnFdG6 meqn3lRcuPt9s4Cj9TVu3NsoGBzPD4sK3S/cCH2SMWnf2tp1CCLfd6229ZCuPaOZ/G JUXj75IpwKtqrm9tO3RI8oZUjEwnkaPd5AjEcETUE1aASyPXWz9tq71McQZ16+7AYE P0oxsmpGRtxtM4fYRzR6yg9+Xw35K9zZWpTNZHKRvr+xJ+RtjMHFcRwvecMUlhjxD3 4mVznnD/F7yh4x7nECubrBsT4NNwDbwpwnyPUnOu0x9sZZC49wVb9AyiOc3pb+P9/D Emlf8cy7JZjPg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Eric Dumazet , syzbot , "David S . Miller" , Sasha Levin , netdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.4 4/9] inet: annotate date races around sk->sk_txhash Date: Mon, 21 Jun 2021 13:56:02 -0400 Message-Id: <20210621175608.736581-4-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210621175608.736581-1-sashal@kernel.org> References: <20210621175608.736581-1-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 b71eaed8c04f72a919a9c44e83e4ee254e69e7f3 ] UDP sendmsg() path can be lockless, it is possible for another thread to re-connect an change sk->sk_txhash under us. There is no serious impact, but we can use READ_ONCE()/WRITE_ONCE() pair to document the race. BUG: KCSAN: data-race in __ip4_datagram_connect / skb_set_owner_w write to 0xffff88813397920c of 4 bytes by task 30997 on cpu 1: sk_set_txhash include/net/sock.h:1937 [inline] __ip4_datagram_connect+0x69e/0x710 net/ipv4/datagram.c:75 __ip6_datagram_connect+0x551/0x840 net/ipv6/datagram.c:189 ip6_datagram_connect+0x2a/0x40 net/ipv6/datagram.c:272 inet_dgram_connect+0xfd/0x180 net/ipv4/af_inet.c:580 __sys_connect_file net/socket.c:1837 [inline] __sys_connect+0x245/0x280 net/socket.c:1854 __do_sys_connect net/socket.c:1864 [inline] __se_sys_connect net/socket.c:1861 [inline] __x64_sys_connect+0x3d/0x50 net/socket.c:1861 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffff88813397920c of 4 bytes by task 31039 on cpu 0: skb_set_hash_from_sk include/net/sock.h:2211 [inline] skb_set_owner_w+0x118/0x220 net/core/sock.c:2101 sock_alloc_send_pskb+0x452/0x4e0 net/core/sock.c:2359 sock_alloc_send_skb+0x2d/0x40 net/core/sock.c:2373 __ip6_append_data+0x1743/0x21a0 net/ipv6/ip6_output.c:1621 ip6_make_skb+0x258/0x420 net/ipv6/ip6_output.c:1983 udpv6_sendmsg+0x160a/0x16b0 net/ipv6/udp.c:1527 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:642 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg net/socket.c:674 [inline] ____sys_sendmsg+0x360/0x4d0 net/socket.c:2350 ___sys_sendmsg net/socket.c:2404 [inline] __sys_sendmmsg+0x315/0x4b0 net/socket.c:2490 __do_sys_sendmmsg net/socket.c:2519 [inline] __se_sys_sendmmsg net/socket.c:2516 [inline] __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2516 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47 entry_SYSCALL_64_after_hwframe+0x44/0xae value changed: 0xbca3c43d -> 0xfdb309e0 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 31039 Comm: syz-executor.2 Not tainted 5.13.0-rc3-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Signed-off-by: Eric Dumazet Reported-by: syzbot Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- include/net/sock.h | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index 31198b32d912..1b657a3a30b5 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -1728,7 +1728,8 @@ static inline u32 net_tx_rndhash(void) static inline void sk_set_txhash(struct sock *sk) { - sk->sk_txhash = net_tx_rndhash(); + /* This pairs with READ_ONCE() in skb_set_hash_from_sk() */ + WRITE_ONCE(sk->sk_txhash, net_tx_rndhash()); } static inline void sk_rethink_txhash(struct sock *sk) @@ -1980,9 +1981,12 @@ static inline void sock_poll_wait(struct file *filp, static inline void skb_set_hash_from_sk(struct sk_buff *skb, struct sock *sk) { - if (sk->sk_txhash) { + /* This pairs with WRITE_ONCE() in sk_set_txhash() */ + u32 txhash = READ_ONCE(sk->sk_txhash); + + if (txhash) { skb->l4_hash = 1; - skb->hash = sk->sk_txhash; + skb->hash = txhash; } } -- 2.30.2