From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH] tc: oops in em_meta Date: Fri, 25 Jan 2008 15:00:57 -0800 Message-ID: <20080125150057.41776614@deepthought> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org To: David Miller , Thomas Graf Return-path: Received: from mail.vyatta.com ([216.93.170.194]:50652 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760709AbYAYXBP (ORCPT ); Fri, 25 Jan 2008 18:01:15 -0500 Sender: netdev-owner@vger.kernel.org List-ID: If userspace passes a unknown match index into em_meta, then em_meta_change will return an error and the data for the match will not be set. This then causes an null pointer dereference when the cleanup is done in the error path via tcf_em_tree_destroy. Since the tree structure comes kzalloc, it is initialized to NULL. Discovered when testing a new version of tc command against an accidental older kernel. Signed-off-by: Stephen Hemminger --- Patch against net-2.6.25 tree, should be backported to earlier stable kernels as well. --- a/net/sched/em_meta.c 2008-01-25 14:52:08.000000000 -0800 +++ b/net/sched/em_meta.c 2008-01-25 14:52:26.000000000 -0800 @@ -735,11 +735,13 @@ static int em_meta_match(struct sk_buff static inline void meta_delete(struct meta_match *meta) { - struct meta_type_ops *ops = meta_type_ops(&meta->lvalue); + if (meta) { + struct meta_type_ops *ops = meta_type_ops(&meta->lvalue); - if (ops && ops->destroy) { - ops->destroy(&meta->lvalue); - ops->destroy(&meta->rvalue); + if (ops && ops->destroy) { + ops->destroy(&meta->lvalue); + ops->destroy(&meta->rvalue); + } } kfree(meta);