Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 16 Dec 2000 11:03:10 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 16 Dec 2000 11:03:01 -0500 Received: from capitanata.ca.astro.it ([192.167.8.254]:5636 "EHLO capitanata.ca.astro.it") by vger.kernel.org with ESMTP id ; Sat, 16 Dec 2000 11:02:47 -0500 Date: Sat, 16 Dec 2000 17:32:04 +0100 (CET) From: Giacomo Mulas To: linux-kernel@vger.kernel.org Subject: a single fragmented IP packet kills the 2.4.0-t12 kernel Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org It seems that a bad bug (in the netfilter code?) was exposed by the changes from 2.4.0-t11 to t12. If a box has the ip_tables and ip_conntrack modules loaded, sending it a single fragmented IP packet (e.g. with "ping -s 65000") is enough to immediately freeze it. It does not respond to the keyboard, does not write the oops(es) to disk... Some people initially stumbled upon this when trying to use nfs, probably because nfs uses large packets and therefore produces fragmented packets. I also tried reverting the netfilter code to that of test11, but it dies exactly in the same way, so that if the bug is in netfilter it was there already. By the way, the bug is only triggered when using netfilter in native mode: the ipchains compatibility mode apparently works fine. Does anybody have a clue? I need the stateful firewalling capabilities of netfilter. I will gladly help, if possible. But I cannot connect a console to the serial port to capture the oops... And, since we are talking about fragments: where did the ip_always_defrag switch that used to be in /proc/sys/net/ipv4 (in 2.2.x kernels) go? Bye, thanks ________________________________________________________________________ Giacomo Mulas ________________________________________________________________________ OSSERVATORIO ASTRONOMICO Str. 54, Loc. Poggio dei Pini * 09012 Capoterra (CA) Tel.: +39 070 71180 216 Fax : +39 070 71180 222 ________________________________________________________________________ "When the storms are raging around you, stay right where you are" (Freddy Mercury) ________________________________________________________________________ - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/