From patchwork Mon Jun 30 22:35:04 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ben Pfaff X-Patchwork-Id: 365797 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 39D4A1400B7 for ; Tue, 1 Jul 2014 08:42:24 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752098AbaF3WmT (ORCPT ); Mon, 30 Jun 2014 18:42:19 -0400 Received: from na3sys009aog135.obsmtp.com ([74.125.149.84]:47619 "HELO na3sys009aog135.obsmtp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1751333AbaF3WmS (ORCPT ); Mon, 30 Jun 2014 18:42:18 -0400 X-Greylist: delayed 426 seconds by postgrey-1.27 at vger.kernel.org; Mon, 30 Jun 2014 18:42:17 EDT Received: from mail-qa0-f54.google.com ([209.85.216.54]) (using TLSv1) by na3sys009aob135.postini.com ([74.125.148.12]) with SMTP ID DSNKU7HnyTvnUQsd2ooEOBfD/OJYFijBzT51@postini.com; Mon, 30 Jun 2014 15:42:18 PDT Received: by mail-qa0-f54.google.com with SMTP id v10so6902228qac.41 for ; Mon, 30 Jun 2014 15:42:17 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=wKH6FiM6jh45F3BYBNmWHapmUlUkOAmqVFhq8SO0H3Q=; b=gp2BJVDJnp3GNVTiPmdRiOWYzK/fp1+21yZnHWYlPSegiUVbKzWw6LmQk+zb8uG+2b s/d1qVqF6Vi8JjbKUFS5CqxqGLCkO9Fkw5nrp84UTHeaQtVjS8dIkkx2gFVTmRNPp2v0 PIXiCRNFoXj026JVBqEUzA9dluseANXPWS47sNfplRfdG5yqOKiwK9DRzbo4Z9Ev7PWC 8ngzgzOhlJvlt8SOG9prRD8u1suFDkAV0uNCJk0Y8WQvHmgS05BVlncmAXD0Kwj30XLU uVvX1Z4pjZxOe97pHjH7grh6Pb3I4JqQGPfQiJcR//4nLMXj+vr5JYUhTNaxTBwAUSjg ndmg== X-Received: by 10.140.85.102 with SMTP id m93mr62477105qgd.26.1404167711373; Mon, 30 Jun 2014 15:35:11 -0700 (PDT) X-Gm-Message-State: ALoCoQmZn+7Tz/2VMnkFKSWB1wKz7U63e2HFoBEE7Wl/bSND9B57UlU92Qo+7BF7a1K6oQp3Q2MzqMJi4e199lPrf6kbhoVPhEsW70cO3/ufQ+3U+PJOc0xBy9gEf5ao/pOKYVurfs7h X-Received: by 10.140.85.102 with SMTP id m93mr62477091qgd.26.1404167711291; Mon, 30 Jun 2014 15:35:11 -0700 (PDT) Received: from sigsegv.eng.vmware.com. (benpfaff.org. [66.246.76.178]) by mx.google.com with ESMTPSA id y10sm34151125qal.32.2014.06.30.15.35.09 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 30 Jun 2014 15:35:10 -0700 (PDT) From: Ben Pfaff To: netdev@vger.kernel.org Cc: Ben Pfaff Subject: [PATCH] netlink: Fix netlink_recvmsg() handling of error from netlink_dump(). Date: Mon, 30 Jun 2014 15:35:04 -0700 Message-Id: <1404167704-22408-1-git-send-email-blp@nicira.com> X-Mailer: git-send-email 1.7.10.4 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 Signed-off-by: Ben Pfaff --- net/netlink/af_netlink.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c index 15c731f..b7514b3 100644 --- a/net/netlink/af_netlink.c +++ b/net/netlink/af_netlink.c @@ -2483,7 +2483,7 @@ 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); } }