From: Nikolay Borisov Date: Fri, 16 Oct 2015 06:40:28 +0000 (+0300) Subject: netfilter: ipset: Fix sleeping memory allocation in atomic context X-Git-Tag: firefly_0821_release~176^2~865^2~42^2 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=00db674bedd68ff8b5afae9030ff5e04d45d1b4a;p=firefly-linux-kernel-4.4.55.git netfilter: ipset: Fix sleeping memory allocation in atomic context 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 --- diff --git a/net/netfilter/ipset/ip_set_list_set.c b/net/netfilter/ipset/ip_set_list_set.c index a1fe5377a2b3..5a30ce6e8c90 100644 --- 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 *value, const struct ip_set_ext *ext, 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;