From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:53274 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752590AbeA2UIj (ORCPT ); Mon, 29 Jan 2018 15:08:39 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+7b7b518b1228d2743963@syzkaller.appspotmail.com, Neil Horman , Xin Long , Marcelo Ricardo Leitner , "David S. Miller" Subject: [PATCH 3.18 47/52] sctp: do not allow the v4 socket to bind a v4mapped v6 address Date: Mon, 29 Jan 2018 13:57:05 +0100 Message-Id: <20180129123630.227935700@linuxfoundation.org> In-Reply-To: <20180129123628.168904217@linuxfoundation.org> References: <20180129123628.168904217@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org List-ID: 3.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xin Long [ Upstream commit c5006b8aa74599ce19104b31d322d2ea9ff887cc ] The check in sctp_sockaddr_af is not robust enough to forbid binding a v4mapped v6 addr on a v4 socket. The worse thing is that v4 socket's bind_verify would not convert this v4mapped v6 addr to a v4 addr. syzbot even reported a crash as the v4 socket bound a v6 addr. This patch is to fix it by doing the common sa.sa_family check first, then AF_INET check for v4mapped v6 addrs. Fixes: 7dab83de50c7 ("sctp: Support ipv6only AF_INET6 sockets.") Reported-by: syzbot+7b7b518b1228d2743963@syzkaller.appspotmail.com Acked-by: Neil Horman Signed-off-by: Xin Long Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/sctp/socket.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -333,16 +333,14 @@ static struct sctp_af *sctp_sockaddr_af( if (len < sizeof (struct sockaddr)) return NULL; + if (!opt->pf->af_supported(addr->sa.sa_family, opt)) + return NULL; + /* V4 mapped address are really of AF_INET family */ if (addr->sa.sa_family == AF_INET6 && - ipv6_addr_v4mapped(&addr->v6.sin6_addr)) { - if (!opt->pf->af_supported(AF_INET, opt)) - return NULL; - } else { - /* Does this PF support this AF? */ - if (!opt->pf->af_supported(addr->sa.sa_family, opt)) - return NULL; - } + ipv6_addr_v4mapped(&addr->v6.sin6_addr) && + !opt->pf->af_supported(AF_INET, opt)) + return NULL; /* If we get this far, af is valid. */ af = sctp_get_af_specific(addr->sa.sa_family);