[PATCH 4.15 110/146] netfilter: xt_hashlimit: fix lock imbalance

[Greg Kroah-Hartman]

4.15-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Dumazet <edumazet@xxxxxxxxxx>

commit de526f401284e1638d4c97cb5a4c292ac3f37655 upstream.

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@xxxxxxxxxx>
Reported-by: syzkaller <syzkaller@xxxxxxxxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 net/netfilter/xt_hashlimit.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netfilter/xt_hashlimit.c
+++ b/net/netfilter/xt_hashlimit.c
@@ -774,7 +774,7 @@ hashlimit_mt_common(const struct sk_buff
 		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;