net: inet: do not leave a dangling sk pointer in inet_create()

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 <ignat@cloudflare.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20241014153808.51894-7-ignat@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index b24d74616637a0e5fc1183cad927fe7c862104c2..8095e82de8083d6f4c9ffacf497d6c4a1a3b3d84 100644 (file)
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -376,32 +376,30 @@ lookup_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;
 }