net: ipv4: fix a memleak in ip_setup_cork

[ Upstream commit 5dee6d6923458e26966717f2a3eae7d09fc10bf6 ]

When inetdev_valid_mtu fails, cork->opt should be freed if it is
allocated in ip_setup_cork. Otherwise there could be a memleak.

Fixes: 501a90c94510 ("inet: protect against too small mtu values.")
Signed-off-by: Zhipeng Lu <alexious@zju.edu.cn>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20240129091017.2938835-1-alexious@zju.edu.cn
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index 4ab877c..ea02474 100644 (file)
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -1285,6 +1285,12 @@ static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
        if (unlikely(!rt))
                return -EFAULT;
 
+       cork->fragsize = ip_sk_use_pmtu(sk) ?
+                        dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
+
+       if (!inetdev_valid_mtu(cork->fragsize))
+               return -ENETUNREACH;
+
        /*
         * setup for corking.
         */
@@ -1301,12 +1307,6 @@ static int ip_setup_cork(struct sock *sk, struct inet_cork *cork,
                cork->addr = ipc->addr;
        }
 
-       cork->fragsize = ip_sk_use_pmtu(sk) ?
-                        dst_mtu(&rt->dst) : READ_ONCE(rt->dst.dev->mtu);
-
-       if (!inetdev_valid_mtu(cork->fragsize))
-               return -ENETUNREACH;
-
        cork->gso_size = ipc->gso_size;
 
        cork->dst = &rt->dst;