[SCTP]: Fix couple of races between sctp_peeloff() and sctp_rcv().

Validate and update the sk in sctp_rcv() to avoid the race where an
assoc/ep could move to a different socket after we get the sk, but before
the skb is added to the backlog.

Also migrate the skb's in backlog queue to new sk when doing a peeloff.

Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>

1 files changed, 4 insertions, 0 deletions

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index 6a0b1af89932..fb1821d9f338 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5602,8 +5602,12 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
          */
         newsp->type = type;
 
+        spin_lock_bh(&oldsk->sk_lock.slock);
+        /* Migrate the backlog from oldsk to newsk. */
+        sctp_backlog_migrate(assoc, oldsk, newsk);
         /* Migrate the association to the new socket. */
         sctp_assoc_migrate(assoc, newsk);
+        spin_unlock_bh(&oldsk->sk_lock.slock);
 
         /* If the association on the newsk is already closed before accept()
          * is called, set RCV_SHUTDOWN flag.