From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Nikolay Borisov , Jozsef Kadlecsik , Pablo Neira Ayuso Subject: [PATCH 4.2 095/110] netfilter: ipset: Fix sleeping memory allocation in atomic context Date: Fri, 6 Nov 2015 11:19:42 -0800 Message-Id: <20151106191708.937933695@linuxfoundation.org> In-Reply-To: <20151106191703.247930828@linuxfoundation.org> References: <20151106191703.247930828@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: 4.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nikolay Borisov commit 00db674bedd68ff8b5afae9030ff5e04d45d1b4a upstream. Commit 00590fdd5be0 introduced RCU locking in list type and in doing so introduced a memory allocation in list_set_add, which is done in an atomic context, due to the fact that ipset rcu list modifications are serialised with a spin lock. The reason why we can't use a mutex is that in addition to modifying the list with ipset commands, it's also being modified when a particular ipset rule timeout expires aka garbage collection. This gc is triggered from set_cleanup_entries, which in turn is invoked from a timer thus requiring the lock to be bh-safe. Concretely the following call chain can lead to "sleeping function called in atomic context" splat: call_ad -> list_set_uadt -> list_set_uadd -> kzalloc(, GFP_KERNEL). And since GFP_KERNEL allows initiating direct reclaim thus potentially sleeping in the allocation path. To fix the issue change the allocation type to GFP_ATOMIC, to correctly reflect that it is occuring in an atomic context. Fixes: 00590fdd5be0 ("netfilter: ipset: Introduce RCU locking in list type") Signed-off-by: Nikolay Borisov Acked-by: Jozsef Kadlecsik Signed-off-by: Pablo Neira Ayuso Signed-off-by: Greg Kroah-Hartman --- net/netfilter/ipset/ip_set_list_set.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/netfilter/ipset/ip_set_list_set.c +++ b/net/netfilter/ipset/ip_set_list_set.c @@ -297,7 +297,7 @@ list_set_uadd(struct ip_set *set, void * ip_set_timeout_expired(ext_timeout(n, set)))) n = NULL; - e = kzalloc(set->dsize, GFP_KERNEL); + e = kzalloc(set->dsize, GFP_ATOMIC); if (!e) return -ENOMEM; e->id = d->id;