Subject: order 7 allocations from xt_recent

From: Dave Jones <[email-masked]>
Date: Thu, 3 Jan 2013 11:43:15 -0500

We had a report from a user that shows this code trying
to do enormous allocations, which isn't going to work too well..

iptables: page allocation failure: order:7, mode:0xc0d0
Pid: 2822, comm: iptables Not tainted 3.6.10-2.fc17.x86_64 #1
Call Trace:
 [<ffffffff8113130b>] warn_alloc_failed+0xeb/0x150
 [<ffffffff81616576>] ? __alloc_pages_direct_compact+0x17e/0x190
 [<ffffffff81135196>] __alloc_pages_nodemask+0x736/0x990
 [<ffffffff811710e0>] alloc_pages_current+0xb0/0x120
 [<ffffffff8113022a>] __get_free_pages+0x2a/0x80
 [<ffffffff811786d9>] kmalloc_order_trace+0x39/0xb0
 [<ffffffff8117ae3a>] __kmalloc+0x16a/0x1a0
 [<ffffffff8118aa7c>] ? mem_cgroup_bad_page_check+0x1c/0x30
 [<ffffffff81134563>] ? get_page_from_freelist+0x453/0x950
 [<ffffffffa007696e>] recent_mt_check.isra.6+0x16e/0x2c0 [xt_recent]
 [<ffffffffa0076b4b>] recent_mt_check_v0+0x6b/0xa0 [xt_recent]
 [<ffffffff8153fdda>] xt_check_match+0xaa/0x1e0
 [<ffffffff8153f3ab>] ? xt_find_match+0x11b/0x130
 [<ffffffff8153f3ab>] ? xt_find_match+0x11b/0x130
 [<ffffffff8159257c>] check_match+0x3c/0x50
 [<ffffffff81593ccb>] translate_table+0x39b/0x5b0
 [<ffffffff815956f3>] do_ipt_set_ctl+0x133/0x200
 [<ffffffff8153e10b>] nf_setsockopt+0x6b/0x90
 [<ffffffff8161f236>] ? _raw_spin_lock_bh+0x16/0x40
 [<ffffffff8154e41f>] ip_setsockopt+0x8f/0xa0
 [<ffffffff8156f49d>] raw_setsockopt+0x1d/0x30
 [<ffffffff814fcf14>] sock_common_setsockopt+0x14/0x20
 [<ffffffff814fc23c>] sys_setsockopt+0x7c/0xe0
 [<ffffffff816270e9>] system_call_fastpath+0x16/0x1b

which looks like it's this..

        t = kzalloc(sizeof(*t) + sizeof(t->iphash[0]) * ip_list_hash_size,
                    GFP_KERNEL);

Which is initialised thus..

        ip_list_hash_size = 1 << fls(ip_list_tot);

And ip_list_tot is 10000 in this case. Hmm ?

Complete report and setup described in his bug report at https://bugzilla.redhat.com/show_bug.cgi?id=890715

	Dave