linux-kernel - [PATCH v2] ipv6/sit: fix ipip6_tunnel_get

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Date:   Sat, 25 Jun 2022 13:45:24 +0800
From:   zys.zljxml@...il.com
To:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        yoshfuji@...ux-ipv6.org, dsahern@...nel.org
Cc:     kuba@...nel.org, davem@...emloft.net, edumazet@...gle.com,
        eric.dumazet@...il.com, pabeni@...hat.com,
        katrinzhou <katrinzhou@...cent.com>
Subject: [PATCH v2] ipv6/sit: fix ipip6_tunnel_get_prl when memory allocation fails

From: katrinzhou <katrinzhou@...cent.com>

Fix an illegal copy_to_user() attempt when the system fails to
allocate memory for prl due to a lack of memory.

Addresses-Coverity: ("Unused value")
Fixes: 300aaeeaab5f ("[IPV6] SIT: Add SIOCGETPRL ioctl to get/dump PRL.")
Signed-off-by: katrinzhou <katrinzhou@...cent.com>
---

Changes in v2:
- Move the position of label "out"

 net/ipv6/sit.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index c0b138c20992..3330882c0f94 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -323,8 +323,6 @@ static int ipip6_tunnel_get_prl(struct net_device *dev, struct ip_tunnel_prl __u
 		kcalloc(cmax, sizeof(*kp), GFP_KERNEL_ACCOUNT | __GFP_NOWARN) :
 		NULL;
 
-	rcu_read_lock();
-
 	ca = min(t->prl_count, cmax);
 
 	if (!kp) {
@@ -342,6 +340,7 @@ static int ipip6_tunnel_get_prl(struct net_device *dev, struct ip_tunnel_prl __u
 	}
 
 	c = 0;
+	rcu_read_lock();
 	for_each_prl_rcu(t->prl) {
 		if (c >= cmax)
 			break;
@@ -353,7 +352,7 @@ static int ipip6_tunnel_get_prl(struct net_device *dev, struct ip_tunnel_prl __u
 		if (kprl.addr != htonl(INADDR_ANY))
 			break;
 	}
-out:
+
 	rcu_read_unlock();
 
 	len = sizeof(*kp) * c;
@@ -362,7 +361,7 @@ static int ipip6_tunnel_get_prl(struct net_device *dev, struct ip_tunnel_prl __u
 		ret = -EFAULT;
 
 	kfree(kp);
-
+out:
 	return ret;
 }
 
-- 
2.27.0