On Fri, Mar 08, 2019 at 11:48:10AM +0800, Xin Long wrote:

On Fri, Mar 8, 2019 at 2:25 AM Marcelo Ricardo Leitner
[off-list ref] wrote:

quoted

On Sun, Mar 03, 2019 at 05:54:53PM +0800, Xin Long wrote:

quoted

It should fail to create the new sk if sctp_bind_addr_dup() fails
when accepting or peeloff an association.

Signed-off-by: Xin Long <lucien.xin@gmail.com>
---
 net/sctp/socket.c | 34 ++++++++++++++++++++++++----------
 1 file changed, 24 insertions(+), 10 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index a2771b3..22adb8d 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c

@@ -102,9 +102,9 @@ static int sctp_send_asconf(struct sctp_association *asoc,
                          struct sctp_chunk *chunk);
 static int sctp_do_bind(struct sock *, union sctp_addr *, int);
 static int sctp_autobind(struct sock *sk);
-static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
-                           struct sctp_association *assoc,
-                           enum sctp_socket_type type);
+static int sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
+                          struct sctp_association *assoc,
+                          enum sctp_socket_type type);

 static unsigned long sctp_memory_pressure;
 static atomic_long_t sctp_memory_allocated;

@@ -4655,7 +4655,11 @@ static struct sock *sctp_accept(struct sock *sk, int flags, int *err, bool kern)
      /* Populate the fields of the newsk from the oldsk and migrate the
       * asoc to the newsk.
       */
-     sctp_sock_migrate(sk, newsk, asoc, SCTP_SOCKET_TCP);
+     error = sctp_sock_migrate(sk, newsk, asoc, SCTP_SOCKET_TCP);
+     if (error) {
+             sk_common_release(newsk);
+             newsk = NULL;
+     }

 out:
      release_sock(sk);

@@ -5401,7 +5405,12 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp)
      /* Populate the fields of the newsk from the oldsk and migrate the
       * asoc to the newsk.
       */
-     sctp_sock_migrate(sk, sock->sk, asoc, SCTP_SOCKET_UDP_HIGH_BANDWIDTH);
+     err = sctp_sock_migrate(sk, sock->sk, asoc,
+                             SCTP_SOCKET_UDP_HIGH_BANDWIDTH);
+     if (err) {
+             sock_release(sock);

I'm having a hard time understanding why it needs sock_release() here
and sk_common_release() in the above chunk. AFAICT by here (after
sctp_sock_migrate call) the sockets are pretty much the same. Mind
elaborating please?

In sctp_do_peeloff(),'sock' is 'struct socket' created by sock_create(),
which should be freed by sock_release(struct socket *sock), otherwise
no place takes care of its freeing.
(sock_create() also create sock->sk)

In sctp_accept(), 'newsk' is 'struct sock' created by sk_alloc(), and
it should be freed by sk_common_release(). Note by then sock->sk is not
yet set to 'newsk', so when it return errs, outside can't free newsk
when freeing sock.
(sys_accept() calls sock_alloc() directly that doesn't set sock->sk)

Thanks.

  Marcelo