[PATCH 4.19 06/23] Bluetooth: L2CAP: Add missing checks for invalid DCID

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Sungwoo Kim <iam@sung-woo.kim>

[ Upstream commit 75767213f3d9b97f63694d02260b6a49a2271876 ]

When receiving a connect response we should make sure that the DCID is
within the valid range and that we don't already have another channel
allocated for the same DCID.
Missing checks may violate the specification (BLUETOOTH CORE SPECIFICATION
Version 5.4 | Vol 3, Part A, Page 1046).

Fixes: 40624183c202 ("Bluetooth: L2CAP: Add missing checks for invalid LE DCID")
Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/bluetooth/l2cap_core.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index d91ddcd54e278..fcc471f921895 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4007,6 +4007,10 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
 	result = __le16_to_cpu(rsp->result);
 	status = __le16_to_cpu(rsp->status);
 
+	if (result == L2CAP_CR_SUCCESS && (dcid < L2CAP_CID_DYN_START ||
+					   dcid > L2CAP_CID_DYN_END))
+		return -EPROTO;
+
 	BT_DBG("dcid 0x%4.4x scid 0x%4.4x result 0x%2.2x status 0x%2.2x",
 	       dcid, scid, result, status);
 
@@ -4038,6 +4042,11 @@ static int l2cap_connect_create_rsp(struct l2cap_conn *conn,
 
 	switch (result) {
 	case L2CAP_CR_SUCCESS:
+		if (__l2cap_get_chan_by_dcid(conn, dcid)) {
+			err = -EBADSLT;
+			break;
+		}
+
 		l2cap_state_change(chan, BT_CONFIG);
 		chan->ident = 0;
 		chan->dcid = dcid;
-- 
2.39.2