From mboxrd@z Thu Jan 1 00:00:00 1970 From: Changli Gao Subject: [PATCH] netfilter: fix the race when initializing nf_ct_expect_hash_rnd Date: Mon, 6 Dec 2010 00:26:37 +0800 Message-ID: <1291566397-24318-1-git-send-email-xiaosuo@gmail.com> Cc: netfilter-devel@vger.kernel.org, "David S. Miller" , netdev@vger.kernel.org, Changli Gao To: Patrick McHardy Return-path: Sender: netdev-owner@vger.kernel.org List-Id: netfilter-devel.vger.kernel.org Since nf_ct_expect_dst_hash() may be called without nf_conntrack_lock locked, nf_ct_expect_hash_rnd should be initialized in the atomic way. Signed-off-by: Changli Gao --- net/netfilter/nf_conntrack_expect.c | 12 +++++++----- 1 file changed, 7 insertions(+), 5 deletions(-) diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c index 46e8966..e2bb3ef 100644 --- a/net/netfilter/nf_conntrack_expect.c +++ b/net/netfilter/nf_conntrack_expect.c @@ -34,7 +34,6 @@ EXPORT_SYMBOL_GPL(nf_ct_expect_hsize); static unsigned int nf_ct_expect_hash_rnd __read_mostly; unsigned int nf_ct_expect_max __read_mostly; -static int nf_ct_expect_hash_rnd_initted __read_mostly; static struct kmem_cache *nf_ct_expect_cachep __read_mostly; @@ -77,10 +76,13 @@ static unsigned int nf_ct_expect_dst_hash(const struct nf_conntrack_tuple *tuple { unsigned int hash; - if (unlikely(!nf_ct_expect_hash_rnd_initted)) { - get_random_bytes(&nf_ct_expect_hash_rnd, - sizeof(nf_ct_expect_hash_rnd)); - nf_ct_expect_hash_rnd_initted = 1; + if (unlikely(!nf_ct_expect_hash_rnd)) { + unsigned int rand; + + do { + get_random_bytes(&rand, sizeof(rand)); + } while (!rand); + cmpxchg(&nf_ct_expect_hash_rnd, 0, rand); } hash = jhash2(tuple->dst.u3.all, ARRAY_SIZE(tuple->dst.u3.all),