From patchwork Mon Mar 12 18:15:25 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Neil Horman X-Patchwork-Id: 884723 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=tuxdriver.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 400R561H1Qz9sNd for ; Tue, 13 Mar 2018 05:16:25 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932629AbeCLSQW (ORCPT ); Mon, 12 Mar 2018 14:16:22 -0400 Received: from charlotte.tuxdriver.com ([70.61.120.58]:33477 "EHLO smtp.tuxdriver.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932231AbeCLSQV (ORCPT ); Mon, 12 Mar 2018 14:16:21 -0400 Received: from cpe-2606-a000-111b-40b7-640c-26a-4e16-9225.dyn6.twc.com ([2606:a000:111b:40b7:640c:26a:4e16:9225] helo=localhost) by smtp.tuxdriver.com with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.63) (envelope-from ) id 1evRzU-0002TQ-3Y; Mon, 12 Mar 2018 14:16:13 -0400 From: Neil Horman To: linux-sctp@vger.kernel.org Cc: netdev@vger.kernel.org, Neil Horman , davem@davemloft.net, Xin Long Subject: [PATCH v2] sctp: Fix double free in sctp_sendmsg_to_asoc Date: Mon, 12 Mar 2018 14:15:25 -0400 Message-Id: <20180312181525.21774-1-nhorman@tuxdriver.com> X-Mailer: git-send-email 2.14.3 In-Reply-To: <00000000000017dfe905670110cf@google.com> References: <00000000000017dfe905670110cf@google.com> X-Spam-Score: -2.9 (--) X-Spam-Status: No Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org syzbot/kasan detected a double free in sctp_sendmsg_to_asoc: BUG: KASAN: use-after-free in sctp_association_free+0x7b7/0x930 net/sctp/associola.c:332 Read of size 8 at addr ffff8801d8006ae0 by task syzkaller914861/4202 CPU: 1 PID: 4202 Comm: syzkaller914861 Not tainted 4.16.0-rc4+ #258 Hardware name: Google Google Compute Engine/Google Compute Engine 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x194/0x24d lib/dump_stack.c:53 print_address_description+0x73/0x250 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report+0x23c/0x360 mm/kasan/report.c:412 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 sctp_association_free+0x7b7/0x930 net/sctp/associola.c:332 sctp_sendmsg+0xc67/0x1a80 net/sctp/socket.c:2075 inet_sendmsg+0x11f/0x5e0 net/ipv4/af_inet.c:763 sock_sendmsg_nosec net/socket.c:629 [inline] sock_sendmsg+0xca/0x110 net/socket.c:639 SYSC_sendto+0x361/0x5c0 net/socket.c:1748 SyS_sendto+0x40/0x50 net/socket.c:1716 do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 entry_SYSCALL_64_after_hwframe+0x42/0xb7 This was introduced by commit: f84af33 sctp: factor out sctp_sendmsg_to_asoc from sctp_sendmsg As the newly refactored function moved the wait_for_sndbuf call to a point after the association was connected, allowing for peeloff events to occur, which in turn caused wait_for_sndbuf to return -EPIPE which was not caught by the logic that determines if an association should be freed or not. Fix it the easy way by returning the ordering of sctp_primitive_ASSOCIATE and sctp_wait_for_sndbuf to the old order, to ensure that EPIPE will not happen. Tested by myself using the syzbot reproducers with positive results Signed-off-by: Neil Horman CC: davem@davemloft.net CC: Xin Long Reported-by: syzbot+a4e4112c3aff00c8cfd8@syzkaller.appspotmail.com Reviewed-by: Xin Long --- Change notes v2) * Moved additional calls to restore origional ordering * add sctp prefix --- net/sctp/socket.c | 26 +++++++++++++------------- 1 file changed, 13 insertions(+), 13 deletions(-) diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 7d3476a4860d..4bbfcf9532c2 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -1876,6 +1876,19 @@ static int sctp_sendmsg_to_asoc(struct sctp_association *asoc, goto err; } + if (asoc->pmtu_pending) + sctp_assoc_pending_pmtu(asoc); + + if (sctp_wspace(asoc) < msg_len) + sctp_prsctp_prune(asoc, sinfo, msg_len - sctp_wspace(asoc)); + + if (!sctp_wspace(asoc)) { + timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); + err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len); + if (err) + goto err; + } + if (sctp_state(asoc, CLOSED)) { err = sctp_primitive_ASSOCIATE(net, asoc, NULL); if (err) @@ -1893,19 +1906,6 @@ static int sctp_sendmsg_to_asoc(struct sctp_association *asoc, pr_debug("%s: we associated primitively\n", __func__); } - if (asoc->pmtu_pending) - sctp_assoc_pending_pmtu(asoc); - - if (sctp_wspace(asoc) < msg_len) - sctp_prsctp_prune(asoc, sinfo, msg_len - sctp_wspace(asoc)); - - if (!sctp_wspace(asoc)) { - timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT); - err = sctp_wait_for_sndbuf(asoc, &timeo, msg_len); - if (err) - goto err; - } - datamsg = sctp_datamsg_from_user(asoc, sinfo, &msg->msg_iter); if (IS_ERR(datamsg)) { err = PTR_ERR(datamsg);