Bluetooth: Disallow to change L2CAP_OPTIONS values when connected

L2CAP doesn't permit change like MTU, FCS, TxWindow values while the
connection is alive, we can only set that before the
connection/configuration process. That can lead to bugs in the L2CAP
operation.

Signed-off-by: Gustavo F. Padovan <padovan@profusion.mobi>

1 files changed, 5 insertions, 0 deletions

diff --git a/net/bluetooth/l2cap.c b/net/bluetooth/l2cap.c
index 44a8fb0d6c29..0b54b7dd8401 100644
--- a/net/bluetooth/l2cap.c
+++ b/net/bluetooth/l2cap.c
@@ -1950,6 +1950,11 @@ static int l2cap_sock_setsockopt_old(struct socket *sock, int optname, char __us
 
         switch (optname) {
         case L2CAP_OPTIONS:
+                if (sk->sk_state == BT_CONNECTED) {
+                        err = -EINVAL;
+                        break;
+                }
+
                 opts.imtu     = l2cap_pi(sk)->imtu;
                 opts.omtu     = l2cap_pi(sk)->omtu;
                 opts.flush_to = l2cap_pi(sk)->flush_to;