From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-4000417-1517256716-2-7178694940524057528 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES enda, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1517256715; b=KxsmVurpO8Wmc/Ygt4of7zu9gEMOmyPtyRfSamFpmav5mk2 tVeh3VxnxrpMEj3mTqXaOoDwRDE77Ny6wgtyTedxfYBY7E+SuPf+a9i0jPWEel7j iaSc7VLoUSZPkIHG2vM6HEHCW8L+IkMcktDjEesupIBxVWmOdkpmiXOUxYZkaO/B eYXHkgNp2g2f0tKdrvDJ+m4fdIe+++XiwKuWasIl08WlxApr5ex9cXqPuiKOflTy AmUiWn6HGe6FKM3DjeG2Kva0iiJDVJAe3mhg7jNoVPuN5UTd3GfRHDqkkCIbU+n8 JJqirjNEY3wcs8ZXfjh8TLS4o35LmiXlqpnurVA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1517256715; bh=xJ4VUoclr9S7M+C3Cqm50V1W8R r7sIhc5OC5BUqr/pM=; b=OMlY4vW3gJdHF0qpGb4NfJtzGzmROctI1v6o8kf5Fb jJ3HhBYcQ9vP1e6dsbKhb+N06qUXs33IFLViw5O4Nx/vlULZWNiGua1zSVmqdr1K NdSrOnxsENY9RL7/S4jkNclCX6iKyUeigPTyUpjoQX071WHXwlzKQyTu2JMIM31C hG4uoZDLUiuWyW+CxtRQ504P15Fe5dBzFoGV4QJyK+9wtEH/E6B6NvsB2nTNpNNn FmyqRCXbLbSDCvSaACy3xnWEz47K0rhU++xNf6UfMf41QfIEw5m3nw0ibVgmhZPq 8DwkPxVzgKqCFBYVDAHt7QymvZSvKyp5/NDlsvUOP5Eg== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753797AbeA2ULw (ORCPT ); Mon, 29 Jan 2018 15:11:52 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:33374 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753794AbeA2ULu (ORCPT ); Mon, 29 Jan 2018 15:11:50 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot , Mike Maloney , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.14 27/71] ipv6: fix udpv6 sendmsg crash caused by too small MTU Date: Mon, 29 Jan 2018 13:56:55 +0100 Message-Id: <20180129123829.104250098@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180129123827.271171825@linuxfoundation.org> References: <20180129123827.271171825@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mike Maloney [ Upstream commit 749439bfac6e1a2932c582e2699f91d329658196 ] The logic in __ip6_append_data() assumes that the MTU is at least large enough for the headers. A device's MTU may be adjusted after being added while sendmsg() is processing data, resulting in __ip6_append_data() seeing any MTU. For an mtu smaller than the size of the fragmentation header, the math results in a negative 'maxfraglen', which causes problems when refragmenting any previous skb in the skb_write_queue, leaving it possibly malformed. Instead sendmsg returns EINVAL when the mtu is calculated to be less than IPV6_MIN_MTU. Found by syzkaller: kernel BUG at ./include/linux/skbuff.h:2064! invalid opcode: 0000 [#1] SMP KASAN Dumping ftrace buffer: (ftrace buffer empty) Modules linked in: CPU: 1 PID: 14216 Comm: syz-executor5 Not tainted 4.13.0-rc4+ #2 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8801d0b68580 task.stack: ffff8801ac6b8000 RIP: 0010:__skb_pull include/linux/skbuff.h:2064 [inline] RIP: 0010:__ip6_make_skb+0x18cf/0x1f70 net/ipv6/ip6_output.c:1617 RSP: 0018:ffff8801ac6bf570 EFLAGS: 00010216 RAX: 0000000000010000 RBX: 0000000000000028 RCX: ffffc90003cce000 RDX: 00000000000001b8 RSI: ffffffff839df06f RDI: ffff8801d9478ca0 RBP: ffff8801ac6bf780 R08: ffff8801cc3f1dbc R09: 0000000000000000 R10: ffff8801ac6bf7a0 R11: 43cb4b7b1948a9e7 R12: ffff8801cc3f1dc8 R13: ffff8801cc3f1d40 R14: 0000000000001036 R15: dffffc0000000000 FS: 00007f43d740c700(0000) GS:ffff8801dc100000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f7834984000 CR3: 00000001d79b9000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: ip6_finish_skb include/net/ipv6.h:911 [inline] udp_v6_push_pending_frames+0x255/0x390 net/ipv6/udp.c:1093 udpv6_sendmsg+0x280d/0x31a0 net/ipv6/udp.c:1363 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:633 [inline] sock_sendmsg+0xca/0x110 net/socket.c:643 SYSC_sendto+0x352/0x5a0 net/socket.c:1750 SyS_sendto+0x40/0x50 net/socket.c:1718 entry_SYSCALL_64_fastpath+0x1f/0xbe RIP: 0033:0x4512e9 RSP: 002b:00007f43d740bc08 EFLAGS: 00000216 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00000000007180a8 RCX: 00000000004512e9 RDX: 000000000000002e RSI: 0000000020d08000 RDI: 0000000000000005 RBP: 0000000000000086 R08: 00000000209c1000 R09: 000000000000001c R10: 0000000000040800 R11: 0000000000000216 R12: 00000000004b9c69 R13: 00000000ffffffff R14: 0000000000000005 R15: 00000000202c2000 Code: 9e 01 fe e9 c5 e8 ff ff e8 7f 9e 01 fe e9 4a ea ff ff 48 89 f7 e8 52 9e 01 fe e9 aa eb ff ff e8 a8 b6 cf fd 0f 0b e8 a1 b6 cf fd <0f> 0b 49 8d 45 78 4d 8d 45 7c 48 89 85 78 fe ff ff 49 8d 85 ba RIP: __skb_pull include/linux/skbuff.h:2064 [inline] RSP: ffff8801ac6bf570 RIP: __ip6_make_skb+0x18cf/0x1f70 net/ipv6/ip6_output.c:1617 RSP: ffff8801ac6bf570 Reported-by: syzbot Signed-off-by: Mike Maloney Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv6/ip6_output.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/net/ipv6/ip6_output.c +++ b/net/ipv6/ip6_output.c @@ -1206,14 +1206,16 @@ static int ip6_setup_cork(struct sock *s v6_cork->tclass = ipc6->tclass; if (rt->dst.flags & DST_XFRM_TUNNEL) mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ? - rt->dst.dev->mtu : dst_mtu(&rt->dst); + READ_ONCE(rt->dst.dev->mtu) : dst_mtu(&rt->dst); else mtu = np->pmtudisc >= IPV6_PMTUDISC_PROBE ? - rt->dst.dev->mtu : dst_mtu(rt->dst.path); + READ_ONCE(rt->dst.dev->mtu) : dst_mtu(rt->dst.path); if (np->frag_size < mtu) { if (np->frag_size) mtu = np->frag_size; } + if (mtu < IPV6_MIN_MTU) + return -EINVAL; cork->base.fragsize = mtu; if (dst_allfrag(rt->dst.path)) cork->base.flags |= IPCORK_ALLFRAG;