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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Luiz Augusto von Dentz <luiz.von.dentz@intel.com>,
        Marcel Holtmann <marcel@holtmann.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.15 284/846] Bluetooth: L2CAP: Fix using wrong mode
Date:   Mon, 24 Jan 2022 19:36:41 +0100
Message-Id: <20220124184110.724640275@linuxfoundation.org>
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From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

[ Upstream commit 30d57722732d9736554f85f75f9d7ad5402d192e ]

If user has a set to use SOCK_STREAM the socket would default to
L2CAP_MODE_ERTM which later needs to be adjusted if the destination
address is LE which doesn't support such mode.

Fixes: 15f02b9105625 ("Bluetooth: L2CAP: Add initial code for Enhanced Credit Based Mode")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/bluetooth/l2cap_sock.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index 4574c5cb1b596..251017c69ab7f 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -161,7 +161,11 @@ static int l2cap_sock_bind(struct socket *sock, struct sockaddr *addr, int alen)
 		break;
 	}
 
-	if (chan->psm && bdaddr_type_is_le(chan->src_type))
+	/* Use L2CAP_MODE_LE_FLOWCTL (CoC) in case of LE address and
+	 * L2CAP_MODE_EXT_FLOWCTL (ECRED) has not been set.
+	 */
+	if (chan->psm && bdaddr_type_is_le(chan->src_type) &&
+	    chan->mode != L2CAP_MODE_EXT_FLOWCTL)
 		chan->mode = L2CAP_MODE_LE_FLOWCTL;
 
 	chan->state = BT_BOUND;
@@ -255,7 +259,11 @@ static int l2cap_sock_connect(struct socket *sock, struct sockaddr *addr,
 			return -EINVAL;
 	}
 
-	if (chan->psm && bdaddr_type_is_le(chan->src_type) && !chan->mode)
+	/* Use L2CAP_MODE_LE_FLOWCTL (CoC) in case of LE address and
+	 * L2CAP_MODE_EXT_FLOWCTL (ECRED) has not been set.
+	 */
+	if (chan->psm && bdaddr_type_is_le(chan->src_type) &&
+	    chan->mode != L2CAP_MODE_EXT_FLOWCTL)
 		chan->mode = L2CAP_MODE_LE_FLOWCTL;
 
 	l2cap_sock_init_pid(sk);
-- 
2.34.1