[PATCH 5.18 108/158] amt: do not use amt->nr_tunnels outside of lock

Greg Kroah-Hartman
2022-07-27T17:41:10Z

From: Taehee Yoo <ap420073@gmail.com>

[ Upstream commit 989918482bbccbbce3ba2bb9156eb4c193319983 ]

amt->nr_tunnels is protected by amt->lock.
But, amt_request_handler() has been using this variable without the
amt->lock.
So, it expands context of amt->lock in the amt_request_handler() to
protect amt->nr_tunnels variable.

Fixes: cbc21dc1cfe9 ("amt: add data plane of amt interface")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/amt.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/amt.c b/drivers/net/amt.c
index 4277924ab3b9..acf5ea96652f 100644
--- a/drivers/net/amt.c
+++ b/drivers/net/amt.c
@@ -2679,7 +2679,9 @@ static bool amt_request_handler(struct amt_dev *amt, struct sk_buff *skb)
if (tunnel->ip4 == iph->saddr)
goto send;

+ spin_lock_bh(&amt->lock);
if (amt->nr_tunnels >= amt->max_tunnels) {
+ spin_unlock_bh(&amt->lock);
icmp_ndo_send(skb, ICMP_DEST_UNREACH, ICMP_HOST_UNREACH, 0);
return true;
}
@@ -2687,8 +2689,10 @@ static bool amt_request_handler(struct amt_dev *amt, struct sk_buff *skb)
tunnel = kzalloc(sizeof(*tunnel) +
(sizeof(struct hlist_head) * amt->hash_buckets),
GFP_ATOMIC);
- if (!tunnel)
+ if (!tunnel) {
+ spin_unlock_bh(&amt->lock);
return true;
+ }

tunnel->source_port = udph->source;
tunnel->ip4 = iph->saddr;
@@ -2701,10 +2705,9 @@ static bool amt_request_handler(struct amt_dev *amt, struct sk_buff *skb)

INIT_DELAYED_WORK(&tunnel->gc_wq, amt_tunnel_expire);

- spin_lock_bh(&amt->lock);
list_add_tail_rcu(&tunnel->list, &amt->tunnel_list);
tunnel->key = amt->key;
- amt_update_relay_status(tunnel, AMT_STATUS_RECEIVED_REQUEST, true);
+ __amt_update_relay_status(tunnel, AMT_STATUS_RECEIVED_REQUEST, true);
amt->nr_tunnels++;
mod_delayed_work(amt_wq, &tunnel->gc_wq,
msecs_to_jiffies(amt_gmi(amt)));
--
2.35.1