Patch "netfilter: ipset: Fix sleeping memory allocation in atomic context" has been added to the 4.2-stable tree

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    netfilter: ipset: Fix sleeping memory allocation in atomic context

to the 4.2-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     netfilter-ipset-fix-sleeping-memory-allocation-in-atomic-context.patch
and it can be found in the queue-4.2 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From 00db674bedd68ff8b5afae9030ff5e04d45d1b4a Mon Sep 17 00:00:00 2001
From: Nikolay Borisov <kernel@kyup.com>
Date: Fri, 16 Oct 2015 09:40:28 +0300
Subject: netfilter: ipset: Fix sleeping memory allocation in atomic context

From: Nikolay Borisov <kernel@kyup.com>

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 <kernel@kyup.com>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 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;


Patches currently in stable-queue which might be from kernel@kyup.com are

queue-4.2/netfilter-ipset-fix-sleeping-memory-allocation-in-atomic-context.patch