netfilter: xt_hashlimit: fix lock imbalance

syszkaller found that rcu was not held in hashlimit_mt_common()

We only need to enable BH at this point.

Fixes: bea74641e378 ("netfilter: xt_hashlimit: add rate match mode")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/net/netfilter/xt_hashlimit.c b/net/netfilter/xt_hashlimit.c
index aa96027..66f5aca 100644 (file)
--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -775,7 +775,7 @@ hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par,
                if (!dh->rateinfo.prev_window &&
                    (dh->rateinfo.current_rate <= dh->rateinfo.burst)) {
                        spin_unlock(&dh->lock);
-                       rcu_read_unlock_bh();
+                       local_bh_enable();
                        return !(cfg->mode & XT_HASHLIMIT_INVERT);
                } else {
                        goto overlimit;