From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932970Ab2IUViY (ORCPT ); Fri, 21 Sep 2012 17:38:24 -0400 Received: from rcsinet15.oracle.com ([148.87.113.117]:34270 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758113Ab2IUViW (ORCPT ); Fri, 21 Sep 2012 17:38:22 -0400 Message-ID: <505CDE47.1090300@oracle.com> Date: Fri, 21 Sep 2012 16:38:15 -0500 From: Venkat Venkatsubra User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:9.0) Gecko/20111222 Thunderbird/9.0.1 MIME-Version: 1.0 To: John Jolly CC: linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH] rds: Error on offset mismatch if not loopback References: <20120921213239.GJ14393@linux-tkdk.sfcn.org> In-Reply-To: <20120921213239.GJ14393@linux-tkdk.sfcn.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 9/21/2012 4:32 PM, John Jolly wrote: > Attempting an rds connection from the IP address of an IPoIB interface > to itself causes a kernel panic due to a BUG_ON() being triggered. > Making the test less strict allows rds-ping to work without crashing > the machine. > > A local unprivileged user could use this flaw to crash the system. > > Signed-off-by: John Jolly > --- > net/rds/ib_send.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/net/rds/ib_send.c b/net/rds/ib_send.c > index e590949..7920c85 100644 > --- a/net/rds/ib_send.c > +++ b/net/rds/ib_send.c > @@ -544,7 +544,7 @@ int rds_ib_xmit(struct rds_connection *conn, struct rds_message *rm, > int flow_controlled = 0; > int nr_sig = 0; > > - BUG_ON(off % RDS_FRAG_SIZE); > + BUG_ON(!conn->c_loopback&& off % RDS_FRAG_SIZE); > BUG_ON(hdr_off != 0&& hdr_off != sizeof(struct rds_header)); > > /* Do not send cong updates to IB loopback */ Hi John, How do you trigger this BUG_ON ? With rds-ping I could not hit this condition of non-zero "off % RDS_FRAG_SIZE". rds-ping uses zero byte messages to ping or pong back. How does the "off" become non-zero ? Thanks. Venkat