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netfilter: ipset: Fix sleeping memory allocation in atomic context 

Commit 00590fdd5b 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: 00590fdd5b ("netfilter: ipset: Introduce RCU locking in list type")
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Nikolay Borisov 2015-10-16 09:40:28 +03:00 committed by Pablo Neira Ayuso
parent 514ed62ed3
commit 00db674bed
1 changed files with 1 additions and 1 deletions
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2
net/netfilter/ipset/ip_set_list_set.c
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@ -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;