netfilter: ipset: fix ip_set_list allocation failure

ip_set_create() and ip_set_net_init() attempt to allocate physically
contiguous memory for ip_set_list. If memory is fragmented, the
allocations could easily fail:

        vzctl: page allocation failure: order:7, mode:0xc0d0

        Call Trace:
         dump_stack+0x19/0x1b
         warn_alloc_failed+0x110/0x180
         __alloc_pages_nodemask+0x7bf/0xc60
         alloc_pages_current+0x98/0x110
         kmalloc_order+0x18/0x40
         kmalloc_order_trace+0x26/0xa0
         __kmalloc+0x279/0x290
         ip_set_net_init+0x4b/0x90 [ip_set]
         ops_init+0x3b/0xb0
         setup_net+0xbb/0x170
         copy_net_ns+0xf1/0x1c0
         create_new_namespaces+0xf9/0x180
         copy_namespaces+0x8e/0xd0
         copy_process+0xb61/0x1a00
         do_fork+0x91/0x320

Use kvcalloc() to fallback to 0-order allocations if high order
page isn't available.
Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/ipset/ip_set_core.c

@@ -960,7 +960,7 @@ static int ip_set_create(struct net *net, struct sock *ctnl,
 			/* Wraparound */
 			goto cleanup;
 
-		list = kcalloc(i, sizeof(struct ip_set *), GFP_KERNEL);
+		list = kvcalloc(i, sizeof(struct ip_set *), GFP_KERNEL);
 		if (!list)
 			goto cleanup;
 		/* nfnl mutex is held, both lists are valid */
@@ -972,7 +972,7 @@ static int ip_set_create(struct net *net, struct sock *ctnl,
 		/* Use new list */
 		index = inst->ip_set_max;
 		inst->ip_set_max = i;
-		kfree(tmp);
+		kvfree(tmp);
 		ret = 0;
 	} else if (ret) {
 		goto cleanup;
@@ -2058,7 +2058,7 @@ ip_set_net_init(struct net *net)
 	if (inst->ip_set_max >= IPSET_INVALID_ID)
 		inst->ip_set_max = IPSET_INVALID_ID - 1;
 
-	list = kcalloc(inst->ip_set_max, sizeof(struct ip_set *), GFP_KERNEL);
+	list = kvcalloc(inst->ip_set_max, sizeof(struct ip_set *), GFP_KERNEL);
 	if (!list)
 		return -ENOMEM;
 	inst->is_deleted = false;
@@ -2086,7 +2086,7 @@ ip_set_net_exit(struct net *net)
 		}
 	}
 	nfnl_unlock(NFNL_SUBSYS_IPSET);
-	kfree(rcu_dereference_protected(inst->ip_set_list, 1));
+	kvfree(rcu_dereference_protected(inst->ip_set_list, 1));
 }
 
 static struct pernet_operations ip_set_net_ops = {