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netfilter: xt_hashlimit: fix lock imbalance

PATCH Applied Eric Dumazet 3 participants 3 messages Feb 12, 2018 – Feb 16, 2018

Subsystems (3)
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Eric Dumazet

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#0 lore raw

PATCH 1/1 netfilter: xt_hashlimit: fix lock imbalance

From: Eric Dumazet <[email protected]>

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 <[email protected]>
Reported-by syzkaller <[email protected]>

---
 net/netfilter/xt_hashlimit.c |    2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)
net/netfilter/xt_hashlimit.c +1 -1
index ca6847403ca218c478d208080aab3e3c92a0a615..1fea48b4182f7cd5669b9c5e7100b2735cc590e7 100644
@@ -774,7 +774,7 @@ 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;
Acked-by on v1 1/1
#1 lore raw
Quoted 19 lines · Eric Dumazet

From: Eric Dumazet <[email protected]>

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 <[email protected]>
Reported-by syzkaller <[email protected]>

---
 net/netfilter/xt_hashlimit.c |    2 +-

 1 file changed, 1 insertion(+), 1 deletion(-)
net/netfilter/xt_hashlimit.c +0 -0
index ca6847403ca218c478d208080aab3e3c92a0a615..1fea48b4182f7cd5669b9c5e7100b2735cc590e7 100644

net/netfilter/xt_hashlimit.c hashlimit_mt_common(const struct sk_buff *skb, struct xt_action_param *par, · line 780

Quoted 8 lines
net/netfilter/xt_hashlimit.c +1 -1
@@ -774,7 +774,7 @@ 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;

Thanks for fixing this.

Acked-by Vishwanath Pai <[email protected]>

-Vishwanath