* [PATCH v3] netfilter: ipset: Fix sleeping memory allocation in atomic context
@ 2015-10-16 6:40 Nikolay Borisov
2015-10-16 11:58 ` Jozsef Kadlecsik
0 siblings, 1 reply; 3+ messages in thread
From: Nikolay Borisov @ 2015-10-16 6:40 UTC (permalink / raw)
To: kadlec, eric.dumazet; +Cc: netfilter-devel, pablo, davem, netdev, operations
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")
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Nikolay Borisov <kernel@kyup.com>
---
Changes since v2:
* Massaged the changelog to reflect discussion
on the mailing list
Changes since v1:
* Added acked-by
* Fixed patch header
net/netfilter/ipset/ip_set_list_set.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/netfilter/ipset/ip_set_list_set.c b/net/netfilter/ipset/ip_set_list_set.c
index a1fe537..5a30ce6 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;
--
2.5.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH v3] netfilter: ipset: Fix sleeping memory allocation in atomic context
2015-10-16 6:40 [PATCH v3] netfilter: ipset: Fix sleeping memory allocation in atomic context Nikolay Borisov
@ 2015-10-16 11:58 ` Jozsef Kadlecsik
2015-10-17 10:59 ` Pablo Neira Ayuso
0 siblings, 1 reply; 3+ messages in thread
From: Jozsef Kadlecsik @ 2015-10-16 11:58 UTC (permalink / raw)
To: Nikolay Borisov
Cc: eric.dumazet, netfilter-devel, Pablo Neira Ayuso, David Miller,
netdev, operations
On Fri, 16 Oct 2015, Nikolay Borisov wrote:
> 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")
>
> Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
> Signed-off-by: Nikolay Borisov <kernel@kyup.com>
> ---
>
> Changes since v2:
> * Massaged the changelog to reflect discussion
> on the mailing list
>
> Changes since v1:
> * Added acked-by
> * Fixed patch header
>
>
>
> net/netfilter/ipset/ip_set_list_set.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
The patch is applied in the ipset package tree. Thanks!
Best regards,
Jozsef
-
E-mail : kadlec@blackhole.kfki.hu, kadlecsik.jozsef@wigner.mta.hu
PGP key : http://www.kfki.hu/~kadlec/pgp_public_key.txt
Address : Wigner Research Centre for Physics, Hungarian Academy of Sciences
H-1525 Budapest 114, POB. 49, Hungary
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v3] netfilter: ipset: Fix sleeping memory allocation in atomic context
2015-10-16 11:58 ` Jozsef Kadlecsik
@ 2015-10-17 10:59 ` Pablo Neira Ayuso
0 siblings, 0 replies; 3+ messages in thread
From: Pablo Neira Ayuso @ 2015-10-17 10:59 UTC (permalink / raw)
To: Jozsef Kadlecsik
Cc: Nikolay Borisov, eric.dumazet, netfilter-devel, David Miller,
netdev, operations
On Fri, Oct 16, 2015 at 01:58:55PM +0200, Jozsef Kadlecsik wrote:
> The patch is applied in the ipset package tree. Thanks!
Applied to the nf tree, thanks.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2015-10-16 6:40 [PATCH v3] netfilter: ipset: Fix sleeping memory allocation in atomic context Nikolay Borisov
2015-10-16 11:58 ` Jozsef Kadlecsik
2015-10-17 10:59 ` Pablo Neira Ayuso
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