On Fri, Mar 8, 2019 at 2:25 AM Marcelo Ricardo Leitner
<marcelo.leit...@gmail.com> wrote:
>
> On Sun, Mar 03, 2019 at 05:54:53PM +0800, Xin Long wrote:
> > 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....@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)
