From mboxrd@z Thu Jan 1 00:00:00 1970 From: Greg Kroah-Hartman Subject: Re: for 3.0 : please add "c16a98e ipv6: tcp: fix panic in SYN processing" Date: Fri, 18 Oct 2013 07:34:33 -0700 Message-ID: <20131018143433.GA27502@kroah.com> References: <20131018140442.GA16883@1wt.eu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: David Miller , Eric Dumazet , netdev@vger.kernel.org, stable@vger.kernel.org To: Willy Tarreau Return-path: Content-Disposition: inline In-Reply-To: <20131018140442.GA16883@1wt.eu> Sender: stable-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, Oct 18, 2013 at 04:04:42PM +0200, Willy Tarreau wrote: > Greg, David, > > one of our customers faced a panic in latest 2.6.32 when both somaxconn > and the listen backlog are large on an IPv6 socket. It was also reported > by one haproxy user on the latest RHEL6 kernel a few months ago. We found > that the same bug affects 3.0 up to and including 3.0.100. > > Eric had already spotted that bug and fixed it in 3.2 with the following > patch : > > commit c16a98ed91597b40b22b540c6517103497ef8e74 > Author: Eric Dumazet > Date: Wed Nov 23 15:49:31 2011 -0500 > > ipv6: tcp: fix panic in SYN processing > > commit 72a3effaf633bc ([NET]: Size listen hash tables using backlog > hint) added a bug allowing inet6_synq_hash() to return an out of bound > array index, because of u16 overflow. > > Bug can happen if system admins set net.core.somaxconn & > net.ipv4.tcp_max_syn_backlog sysctls to values greater than 65536 > > Signed-off-by: Eric Dumazet > Signed-off-by: David S. Miller > > In practice, the bug extends to lower values as well (32768 and above), > because reqsk_queue_alloc() can round the number of entries to double of > the backlog by doing roundup_pow_of_two(backlog+1), resulting in > inet6_csk_search_req() calling inet6_synq_hash() with too large an integer. > > Could we please apply it to 3.0 before it finishes its life ? Unless David objects, I can queue this up just in time for the last 3.0.stable. David?