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=-11.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 72FBFC43465 for ; Mon, 21 Sep 2020 16:43:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1F7DE2399A for ; Mon, 21 Sep 2020 16:43:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600706629; bh=DopP0TXFS0MBEU+sZLrZgDrgeACAe7ZZZdRuOn1hAGE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=kWbVN19ZtJxddEdiF0ZAWACs2FDbAhw+q8kUhMr7IEeMiqrX9NIuYoeJ7TyKdiogg 4+XjJ9O2AydAkR7cRh9pr526ZT/VW8e9BLa9I/NYGnDKN2/In+zwTqeOZpdn6vHF+W n0gaiokVHwj133lMaz8A3hQiIxgFw3MM6TN4XiuA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728925AbgIUQno (ORCPT ); Mon, 21 Sep 2020 12:43:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:48210 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729617AbgIUQnd (ORCPT ); Mon, 21 Sep 2020 12:43:33 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 41C4B23A1E; Mon, 21 Sep 2020 16:43:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1600706612; bh=DopP0TXFS0MBEU+sZLrZgDrgeACAe7ZZZdRuOn1hAGE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=BW0tqI9R91nI2swdLdep9V1p8LhEhhQjr5c1cuBXuGQ5X5a1k+iZGHemqdofJ7aO3 BVNeAHwfeXqZzYCuJ/byxBOsM1TkPlg7RyR8hys/+CazXx0Jl/JSYjtnQQ9YnByjLr yFosKdhObpZFArb3ROo0ySiXjEALr5QqUzrquv+w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Florian Westphal , Mat Martineau , "David S. Miller" Subject: [PATCH 5.8 003/118] mptcp: sendmsg: reset iter on error Date: Mon, 21 Sep 2020 18:26:55 +0200 Message-Id: <20200921162036.501567458@linuxfoundation.org> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20200921162036.324813383@linuxfoundation.org> References: <20200921162036.324813383@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Florian Westphal commit 35759383133f64d90eba120a0d3efe8f71241650 upstream. 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 Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/mptcp/protocol.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -605,8 +605,10 @@ static int mptcp_sendmsg_frag(struct soc 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); @@ -617,8 +619,10 @@ static int mptcp_sendmsg_frag(struct soc */ 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) {