From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754269AbaGZT7g (ORCPT ); Sat, 26 Jul 2014 15:59:36 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:33826 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752769AbaGZTDJ (ORCPT ); Sat, 26 Jul 2014 15:03:09 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ben Pfaff , "David S. Miller" Subject: [PATCH 3.10 33/56] netlink: Fix handling of error from netlink_dump(). Date: Sat, 26 Jul 2014 12:02:26 -0700 Message-Id: <20140726190201.140467696@linuxfoundation.org> X-Mailer: git-send-email 2.0.2 In-Reply-To: <20140726190200.061512159@linuxfoundation.org> References: <20140726190200.061512159@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Pfaff [ Upstream commit ac30ef832e6af0505b6f0251a6659adcfa74975e ] netlink_dump() returns a negative errno value on error. Until now, netlink_recvmsg() directly recorded that negative value in sk->sk_err, but that's wrong since sk_err takes positive errno values. (This manifests as userspace receiving a positive return value from the recv() system call, falsely indicating success.) This bug was introduced in the commit that started checking the netlink_dump() return value, commit b44d211 (netlink: handle errors from netlink_dump()). Multithreaded Netlink dumps are one way to trigger this behavior in practice, as described in the commit message for the userspace workaround posted here: http://openvswitch.org/pipermail/dev/2014-June/042339.html This commit also fixes the same bug in netlink_poll(), introduced in commit cd1df525d (netlink: add flow control for memory mapped I/O). Signed-off-by: Ben Pfaff Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/netlink/af_netlink.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -500,7 +500,7 @@ static unsigned int netlink_poll(struct while (nlk->cb != NULL && netlink_dump_space(nlk)) { err = netlink_dump(sk); if (err < 0) { - sk->sk_err = err; + sk->sk_err = -err; sk->sk_error_report(sk); break; } @@ -2272,7 +2272,7 @@ static int netlink_recvmsg(struct kiocb if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) { ret = netlink_dump(sk); if (ret) { - sk->sk_err = ret; + sk->sk_err = -ret; sk->sk_error_report(sk); } }