sctp: hold transport instead of assoc in sctp_diag

In sctp_transport_lookup_process(), Commit 1cceda784980 ("sctp: fix
the issue sctp_diag uses lock_sock in rcu_read_lock") moved cb() out
of rcu lock, but it put transport and hold assoc instead, and ignore
that cb() still uses transport. It may cause a use-after-free issue.

This patch is to hold transport instead of assoc there.

Fixes: 1cceda784980 ("sctp: fix the issue sctp_diag uses lock_sock in rcu_read_lock")
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 1 insertions, 4 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 9fbb6feb8c27..71b75f9d9c1b 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -4480,12 +4480,9 @@ int sctp_transport_lookup_process(int (*cb)(struct sctp_transport *, void *),
         if (!transport || !sctp_transport_hold(transport))
                 goto out;
 
-        sctp_association_hold(transport->asoc);
-        sctp_transport_put(transport);
-
         rcu_read_unlock();
         err = cb(transport, p);
-        sctp_association_put(transport->asoc);
+        sctp_transport_put(transport);
 
 out:
         return err;