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| author | Pablo Neira Ayuso <pablo@netfilter.org> | 2013-11-18 12:53:59 +0100 |
|---|---|---|
| committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2013-11-18 14:07:19 +0100 |
| commit | 0c3c6c00c69649f4749642b3e5d82125fde1600c (patch) | |
| tree | 714027963159c08729d3fabd21338338acec6f7c | |
| parent | netfilter: nft_compat: fix error path in nft_parse_compat() (diff) | |
| download | linux-0c3c6c00c69649f4749642b3e5d82125fde1600c.tar.xz linux-0c3c6c00c69649f4749642b3e5d82125fde1600c.zip | |
netfilter: nf_conntrack: decrement global counter after object release
nf_conntrack_free() decrements our counter (net->ct.count)
before releasing the conntrack object. That counter is used in the
nf_conntrack_cleanup_net_list path to check if it's time to
kmem_cache_destroy our cache of conntrack objects. I think we have
a race there that should be easier to trigger (although still hard)
with CONFIG_DEBUG_OBJECTS_FREE as object releases become slowier
according to the following splat:
[ 1136.321305] WARNING: CPU: 2 PID: 2483 at lib/debugobjects.c:260
debug_print_object+0x83/0xa0()
[ 1136.321311] ODEBUG: free active (active state 0) object type:
timer_list hint: delayed_work_timer_fn+0x0/0x20
...
[ 1136.321390] Call Trace:
[ 1136.321398] [<ffffffff8160d4a2>] dump_stack+0x45/0x56
[ 1136.321405] [<ffffffff810514e8>] warn_slowpath_common+0x78/0xa0
[ 1136.321410] [<ffffffff81051557>] warn_slowpath_fmt+0x47/0x50
[ 1136.321414] [<ffffffff812f8883>] debug_print_object+0x83/0xa0
[ 1136.321420] [<ffffffff8106aa90>] ? execute_in_process_context+0x90/0x90
[ 1136.321424] [<ffffffff812f99fb>] debug_check_no_obj_freed+0x20b/0x250
[ 1136.321429] [<ffffffff8112e7f2>] ? kmem_cache_destroy+0x92/0x100
[ 1136.321433] [<ffffffff8115d945>] kmem_cache_free+0x125/0x210
[ 1136.321436] [<ffffffff8112e7f2>] kmem_cache_destroy+0x92/0x100
[ 1136.321443] [<ffffffffa046b806>] nf_conntrack_cleanup_net_list+0x126/0x160 [nf_conntrack]
[ 1136.321449] [<ffffffffa046c43d>] nf_conntrack_pernet_exit+0x6d/0x80 [nf_conntrack]
[ 1136.321453] [<ffffffff81511cc3>] ops_exit_list.isra.3+0x53/0x60
[ 1136.321457] [<ffffffff815124f0>] cleanup_net+0x100/0x1b0
[ 1136.321460] [<ffffffff8106b31e>] process_one_work+0x18e/0x430
[ 1136.321463] [<ffffffff8106bf49>] worker_thread+0x119/0x390
[ 1136.321467] [<ffffffff8106be30>] ? manage_workers.isra.23+0x2a0/0x2a0
[ 1136.321470] [<ffffffff8107210b>] kthread+0xbb/0xc0
[ 1136.321472] [<ffffffff81072050>] ? kthread_create_on_node+0x110/0x110
[ 1136.321477] [<ffffffff8161b8fc>] ret_from_fork+0x7c/0xb0
[ 1136.321479] [<ffffffff81072050>] ? kthread_create_on_node+0x110/0x110
[ 1136.321481] ---[ end trace 25f53c192da70825 ]---
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
| -rw-r--r-- | net/netfilter/nf_conntrack_core.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c index e22d950c60b3..43549eb7a7be 100644 --- a/net/netfilter/nf_conntrack_core.c +++ b/net/netfilter/nf_conntrack_core.c @@ -764,9 +764,10 @@ void nf_conntrack_free(struct nf_conn *ct) struct net *net = nf_ct_net(ct); nf_ct_ext_destroy(ct); - atomic_dec(&net->ct.count); nf_ct_ext_free(ct); kmem_cache_free(net->ct.nf_conntrack_cachep, ct); + smp_mb__before_atomic_dec(); + atomic_dec(&net->ct.count); } EXPORT_SYMBOL_GPL(nf_conntrack_free); |