sctp: Don't call sk->sk_prot->init() in sctp_v[46]_create_accept_sk().

sctp_accept() calls sctp_v[46]_create_accept_sk() to allocate a new
socket and calls sctp_sock_migrate() to copy fields from the parent
socket to the new socket.

sctp_v[46]_create_accept_sk() calls sctp_init_sock() to initialise
sctp_sock, but most fields are overwritten by sctp_copy_descendant()
called from sctp_sock_migrate().

Things done in sctp_init_sock() but not in sctp_sock_migrate() are
the following:

  1. Copy sk->sk_gso
  2. Copy sk->sk_destruct (sctp_v6_init_sock())
  3. Allocate sctp_sock.ep
  4. Initialise sctp_sock.pd_lobby
  5. Count sk_sockets_allocated_inc(), sock_prot_inuse_add(),
     and SCTP_DBG_OBJCNT_INC()

Let's do these in sctp_copy_sock() and sctp_sock_migrate() and avoid
calling sk->sk_prot->init() in sctp_v[46]_create_accept_sk().

Note that sk->sk_destruct is already copied in sctp_copy_sock().

Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Acked-by: Xin Long <lucien.xin@gmail.com>
Link: https://patch.msgid.link/20251023231751.4168390-4-kuniyu@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

1 files changed, 1 insertions, 7 deletions

diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 9dbc24af749b..ad2722d1ec15 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -590,7 +590,7 @@ static struct sock *sctp_v4_create_accept_sk(struct sock *sk,
 	struct inet_sock *newinet;
 
 	if (!newsk)
-		goto out;
+		return NULL;
 
 	sock_init_data(NULL, newsk);
 
@@ -603,12 +603,6 @@ static struct sock *sctp_v4_create_accept_sk(struct sock *sk,
 
 	newinet->inet_daddr = asoc->peer.primary_addr.v4.sin_addr.s_addr;
 
-	if (newsk->sk_prot->init(newsk)) {
-		sk_common_release(newsk);
-		newsk = NULL;
-	}
-
-out:
 	return newsk;
 }