[PATCH v1] Bluetooth: L2CAP: Fix invalid response to L2CAP_ECRED_RECONF_REQ

[Luiz Augusto von Dentz <luiz.dentz@gmail.com>]

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

This fixes responding with an invalid result caused by checking the
wrong size of CID which should have been (cmd_len - sizeof(*req)) and
on top of it the wrong result was use L2CAP_CR_LE_INVALID_PARAMS which
is invalid/reserved for reconf when running test like L2CAP/ECFC/BI-03-C:

> ACL Data RX: Handle 64 flags 0x02 dlen 14
      LE L2CAP: Enhanced Credit Reconfigure Request (0x19) ident 2 len 6
        MTU: 64
        MPS: 64
        Source CID: 64
< ACL Data TX: Handle 64 flags 0x00 dlen 10https://github.com/bluez/bluez/issues/1865
      LE L2CAP: Enhanced Credit Reconfigure Respond (0x1a) ident 2 len 2
        Result: Reserved (0x000c)

So this fix the check and introduce the error L2CAP_RECONF_INVALID_CID
(0x0003).

Link: https://github.com/bluez/bluez/issues/1865
Fixes: 15f02b910562 ("Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 include/net/bluetooth/l2cap.h | 2 ++
 net/bluetooth/l2cap_core.c    | 4 ++--
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/net/bluetooth/l2cap.h b/include/net/bluetooth/l2cap.h
index ec3af01e4db9..6f9cf7a05986 100644
--- a/include/net/bluetooth/l2cap.h
+++ b/include/net/bluetooth/l2cap.h
@@ -493,6 +493,8 @@ struct l2cap_ecred_reconf_req {
 #define L2CAP_RECONF_SUCCESS		0x0000
 #define L2CAP_RECONF_INVALID_MTU	0x0001
 #define L2CAP_RECONF_INVALID_MPS	0x0002
+#define L2CAP_RECONF_INVALID_CID	0x0003
+#define L2CAP_RECONF_INVALID_PARAMS	0x0004
 
 struct l2cap_ecred_reconf_rsp {
 	__le16 result;
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index b628b0fa39b2..7f1d80086655 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -5316,8 +5316,8 @@ static inline int l2cap_ecred_reconf_req(struct l2cap_conn *conn,
 	if (!enable_ecred)
 		return -EINVAL;
 
-	if (cmd_len < sizeof(*req) || cmd_len - sizeof(*req) % sizeof(u16)) {
-		result = L2CAP_CR_LE_INVALID_PARAMS;
+	if (cmd_len < sizeof(*req) || (cmd_len - sizeof(*req)) % sizeof(u16)) {
+		result = L2CAP_RECONF_INVALID_CID;
 		goto respond;
 	}
 
-- 
2.52.0