From patchwork Fri Aug 14 13:56:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Westphal X-Patchwork-Id: 1345045 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming-netdev@ozlabs.org Delivered-To: patchwork-incoming-netdev@ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=strlen.de Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BSlNw2Dpkz9sTW for ; Fri, 14 Aug 2020 23:57:04 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727021AbgHNN4v (ORCPT ); Fri, 14 Aug 2020 09:56:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60902 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726196AbgHNN4v (ORCPT ); Fri, 14 Aug 2020 09:56:51 -0400 Received: from Chamillionaire.breakpoint.cc (Chamillionaire.breakpoint.cc [IPv6:2a0a:51c0:0:12e:520::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 19F49C061384 for ; Fri, 14 Aug 2020 06:56:50 -0700 (PDT) Received: from fw by Chamillionaire.breakpoint.cc with local (Exim 4.92) (envelope-from ) id 1k6aCN-0008WG-IV; Fri, 14 Aug 2020 15:56:47 +0200 From: Florian Westphal To: Cc: mathew.j.martineau@linux.intel.com, matthieu.baerts@tessares.net, mptcp@lists.01.org, Florian Westphal Subject: [PATCH net] mptcp: sendmsg: reset iter on error Date: Fri, 14 Aug 2020 15:56:34 +0200 Message-Id: <20200814135634.12996-1-fw@strlen.de> X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Once we've copied data from the iterator we need to revert in case we end up not sending any data. This bug doesn't trigger with normal 'poll' based tests, because we only feed a small chunk of data to kernel after poll indicated POLLOUT. With blocking IO and large writes this triggers. Receiver ends up with less data than it should get. Fixes: 72511aab95c94d ("mptcp: avoid blocking in tcp_sendpages") Signed-off-by: Florian Westphal Reviewed-by: Mat Martineau --- net/mptcp/protocol.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index d5aaa98b9136..2e7e87304930 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -725,8 +725,10 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, if (!psize) return -EINVAL; - if (!sk_wmem_schedule(sk, psize + dfrag->overhead)) + if (!sk_wmem_schedule(sk, psize + dfrag->overhead)) { + iov_iter_revert(&msg->msg_iter, psize); return -ENOMEM; + } } else { offset = dfrag->offset; psize = min_t(size_t, dfrag->data_len, avail_size); @@ -737,8 +739,10 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk, */ ret = do_tcp_sendpages(ssk, page, offset, psize, msg->msg_flags | MSG_SENDPAGE_NOTLAST | MSG_DONTWAIT); - if (ret <= 0) + if (ret <= 0) { + iov_iter_revert(&msg->msg_iter, psize); return ret; + } frag_truesize += ret; if (!retransmission) {