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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham 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 21D7AFC6195 for ; Fri, 8 Nov 2019 19:00:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EF12220865 for ; Fri, 8 Nov 2019 19:00:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573239614; bh=VF547Q+UrNwRXr4sDr3Y7MlkbWR5j1ZST7OYdWdPn2Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gbxIakYdhFIR6caAxxN9XTiJRJr3IkTcC90/3PsT6bsATX3nDyRb26cyCu1i18oyK ++xp6I3dartaS6usr/CYC8vRNAF0/C1w3rjrXs4BDFZLu7FDDREkhaPSahAOzqbb90 1ZcjKYS4Unps0MQrrGzzKJqqR1AfSb6/nLowQBfE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389569AbfKHTAN (ORCPT ); Fri, 8 Nov 2019 14:00:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:57238 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389524AbfKHTAM (ORCPT ); Fri, 8 Nov 2019 14:00:12 -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 E3873224A1; Fri, 8 Nov 2019 18:58:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1573239525; bh=VF547Q+UrNwRXr4sDr3Y7MlkbWR5j1ZST7OYdWdPn2Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mi1Uk+ZWg4jClYXjeGbC6lZe4lsbh19g1SpM3FMouZuTtF2BDI/UNWpPHyy+f+Pwf /MWDyMeuBCQOelORlkK680v8n9nsd9YDqsVymZUGLajW7jXuwgJ7FbNttibN1R2XPr vw3lJXsX5Y7vAlHA5M+WYC6tLRKYF+rNUpqDICf4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , syzbot , Paolo Abeni , "David S. Miller" Subject: [PATCH 4.14 34/62] udp: fix data-race in udp_set_dev_scratch() Date: Fri, 8 Nov 2019 19:50:22 +0100 Message-Id: <20191108174745.061425151@linuxfoundation.org> X-Mailer: git-send-email 2.24.0 In-Reply-To: <20191108174719.228826381@linuxfoundation.org> References: <20191108174719.228826381@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet [ Upstream commit a793183caa9afae907a0d7ddd2ffd57329369bf5 ] KCSAN reported a data-race in udp_set_dev_scratch() [1] The issue here is that we must not write over skb fields if skb is shared. A similar issue has been fixed in commit 89c22d8c3b27 ("net: Fix skb csum races when peeking") While we are at it, use a helper only dealing with udp_skb_scratch(skb)->csum_unnecessary, as this allows udp_set_dev_scratch() to be called once and thus inlined. [1] BUG: KCSAN: data-race in udp_set_dev_scratch / udpv6_recvmsg write to 0xffff888120278317 of 1 bytes by task 10411 on cpu 1: udp_set_dev_scratch+0xea/0x200 net/ipv4/udp.c:1308 __first_packet_length+0x147/0x420 net/ipv4/udp.c:1556 first_packet_length+0x68/0x2a0 net/ipv4/udp.c:1579 udp_poll+0xea/0x110 net/ipv4/udp.c:2720 sock_poll+0xed/0x250 net/socket.c:1256 vfs_poll include/linux/poll.h:90 [inline] do_select+0x7d0/0x1020 fs/select.c:534 core_sys_select+0x381/0x550 fs/select.c:677 do_pselect.constprop.0+0x11d/0x160 fs/select.c:759 __do_sys_pselect6 fs/select.c:784 [inline] __se_sys_pselect6 fs/select.c:769 [inline] __x64_sys_pselect6+0x12e/0x170 fs/select.c:769 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 read to 0xffff888120278317 of 1 bytes by task 10413 on cpu 0: udp_skb_csum_unnecessary include/net/udp.h:358 [inline] udpv6_recvmsg+0x43e/0xe90 net/ipv6/udp.c:310 inet6_recvmsg+0xbb/0x240 net/ipv6/af_inet6.c:592 sock_recvmsg_nosec+0x5c/0x70 net/socket.c:871 ___sys_recvmsg+0x1a0/0x3e0 net/socket.c:2480 do_recvmmsg+0x19a/0x5c0 net/socket.c:2601 __sys_recvmmsg+0x1ef/0x200 net/socket.c:2680 __do_sys_recvmmsg net/socket.c:2703 [inline] __se_sys_recvmmsg net/socket.c:2696 [inline] __x64_sys_recvmmsg+0x89/0xb0 net/socket.c:2696 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 10413 Comm: syz-executor.0 Not tainted 5.4.0-rc3+ #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Fixes: 2276f58ac589 ("udp: use a separate rx queue for packet reception") Signed-off-by: Eric Dumazet Reported-by: syzbot Cc: Paolo Abeni Reviewed-by: Paolo Abeni Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/udp.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1195,6 +1195,20 @@ static void udp_set_dev_scratch(struct s scratch->_tsize_state |= UDP_SKB_IS_STATELESS; } +static void udp_skb_csum_unnecessary_set(struct sk_buff *skb) +{ + /* We come here after udp_lib_checksum_complete() returned 0. + * This means that __skb_checksum_complete() might have + * set skb->csum_valid to 1. + * On 64bit platforms, we can set csum_unnecessary + * to true, but only if the skb is not shared. + */ +#if BITS_PER_LONG == 64 + if (!skb_shared(skb)) + udp_skb_scratch(skb)->csum_unnecessary = true; +#endif +} + static int udp_skb_truesize(struct sk_buff *skb) { return udp_skb_scratch(skb)->_tsize_state & ~UDP_SKB_IS_STATELESS; @@ -1430,10 +1444,7 @@ static struct sk_buff *__first_packet_le *total += skb->truesize; kfree_skb(skb); } else { - /* the csum related bits could be changed, refresh - * the scratch area - */ - udp_set_dev_scratch(skb); + udp_skb_csum_unnecessary_set(skb); break; } }