Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754953AbaG3M3S (ORCPT ); Wed, 30 Jul 2014 08:29:18 -0400 Received: from ip4-83-240-18-248.cust.nbox.cz ([83.240.18.248]:36752 "EHLO ip4-83-240-18-248.cust.nbox.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752933AbaG3MPd (ORCPT ); Wed, 30 Jul 2014 08:15:33 -0400 From: Jiri Slaby To: stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Ben Pfaff , "David S. Miller" , Jiri Slaby Subject: [PATCH 3.12 50/94] netlink: Fix handling of error from netlink_dump(). Date: Wed, 30 Jul 2014 14:14:39 +0200 Message-Id: <8df19ce788d3d18eb4054862daa55a7ee4c883b0.1406722270.git.jslaby@suse.cz> X-Mailer: git-send-email 2.0.1 In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ben Pfaff 3.12-stable review patch. If anyone has any objections, please let me know. =============== [ 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: Jiri Slaby --- net/netlink/af_netlink.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index e6d457c4a4e4..d9a2598a5190 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -628,7 +628,7 @@ static unsigned int netlink_poll(struct file *file, struct socket *sock, while (nlk->cb_running && 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; } @@ -2440,7 +2440,7 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock, 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); } } -- 2.0.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/