From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754600Ab2AWXpY (ORCPT ); Mon, 23 Jan 2012 18:45:24 -0500 Received: from cantor2.suse.de ([195.135.220.15]:41946 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753654Ab2AWXpV (ORCPT ); Mon, 23 Jan 2012 18:45:21 -0500 X-Mailbox-Line: From gregkh@clark.kroah.org Mon Jan 23 15:42:03 2012 Message-Id: <20120123234203.025513019@clark.kroah.org> User-Agent: quilt/0.50-11.1 Date: Mon, 23 Jan 2012 15:41:02 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, "J. Bruce Fields" Subject: [16/27] svcrpc: fix double-free on shutdown of nfsd after changing pool mode In-Reply-To: <20120123234224.GA19510@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm review patch. If anyone has any objections, please let me know. ------------------ From: "J. Bruce Fields" commit 61c8504c428edcebf23b97775a129c5b393a302b upstream. The pool_to and to_pool fields of the global svc_pool_map are freed on shutdown, but are initialized in nfsd startup only in the SVC_POOL_PERCPU and SVC_POOL_PERNODE cases. They *are* initialized to zero on kernel startup. So as long as you use only SVC_POOL_GLOBAL (the default), this will never be a problem. You're also OK if you only ever use SVC_POOL_PERCPU or SVC_POOL_PERNODE. However, the following sequence events leads to a double-free: 1. set SVC_POOL_PERCPU or SVC_POOL_PERNODE 2. start nfsd: both fields are initialized. 3. shutdown nfsd: both fields are freed. 4. set SVC_POOL_GLOBAL 5. start nfsd: the fields are left untouched. 6. shutdown nfsd: now we try to free them again. Step 4 is actually unnecessary, since (for some bizarre reason), nfsd automatically resets the pool mode to SVC_POOL_GLOBAL on shutdown. Signed-off-by: J. Bruce Fields Signed-off-by: Greg Kroah-Hartman --- net/sunrpc/svc.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/sunrpc/svc.c +++ b/net/sunrpc/svc.c @@ -166,6 +166,7 @@ svc_pool_map_alloc_arrays(struct svc_poo fail_free: kfree(m->to_pool); + m->to_pool = NULL; fail: return -ENOMEM; } @@ -286,7 +287,9 @@ svc_pool_map_put(void) if (!--m->count) { m->mode = SVC_POOL_DEFAULT; kfree(m->to_pool); + m->to_pool = NULL; kfree(m->pool_to); + m->pool_to = NULL; m->npools = 0; }