[PATCH net-next v3 6/9] net: inet: do not leave a dangling sk pointer in inet_create()

[Ignat Korchagin]

sock_init_data() attaches the allocated sk object to the provided sock
object. If inet_create() fails later, the sk object is freed, but the
sock object retains the dangling pointer, which may create use-after-free
later.

Clear the sk pointer in the sock object on error.

Signed-off-by: Ignat Korchagin <ig...@cloudflare.com>
---
 net/ipv4/af_inet.c | 22 ++++++++++------------
 1 file changed, 10 insertions(+), 12 deletions(-)

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index b24d74616637..8095e82de808 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -376,32 +376,30 @@ static int inet_create(struct net *net, struct socket 
*sock, int protocol,
                inet->inet_sport = htons(inet->inet_num);
                /* Add to protocol hash chains. */
                err = sk->sk_prot->hash(sk);
-               if (err) {
-                       sk_common_release(sk);
-                       goto out;
-               }
+               if (err)
+                       goto out_sk_release;
        }
 
        if (sk->sk_prot->init) {
                err = sk->sk_prot->init(sk);
-               if (err) {
-                       sk_common_release(sk);
-                       goto out;
-               }
+               if (err)
+                       goto out_sk_release;
        }
 
        if (!kern) {
                err = BPF_CGROUP_RUN_PROG_INET_SOCK(sk);
-               if (err) {
-                       sk_common_release(sk);
-                       goto out;
-               }
+               if (err)
+                       goto out_sk_release;
        }
 out:
        return err;
 out_rcu_unlock:
        rcu_read_unlock();
        goto out;
+out_sk_release:
+       sk_common_release(sk);
+       sock->sk = NULL;
+       goto out;
 }
 
 
-- 
2.39.5