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[v2] Bluetooth: L2CAP: Fix L2CAP_ECRED_CONN_RSP response

Message ID 20250218175123.1479657-1-luiz.dentz@gmail.com
State New
Headers show
Series [v2] Bluetooth: L2CAP: Fix L2CAP_ECRED_CONN_RSP response | expand

Commit Message

Luiz Augusto von Dentz Feb. 18, 2025, 5:51 p.m. UTC 
From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

L2CAP_ECRED_CONN_RSP needs to respond DCID in the same order received as
SCID but the order is reversed due to use of list_add which actually
prepend channels to the list so the response is reversed:

> ACL Data RX: Handle 16 flags 0x02 dlen 26
      LE L2CAP: Enhanced Credit Connection Request (0x17) ident 2 len 18
        PSM: 39 (0x0027)
        MTU: 256
        MPS: 251
        Credits: 65535
        Source CID: 116
        Source CID: 117
        Source CID: 118
        Source CID: 119
        Source CID: 120
< ACL Data TX: Handle 16 flags 0x00 dlen 26
      LE L2CAP: Enhanced Credit Connection Response (0x18) ident 2 len 18
        MTU: 517
        MPS: 247
        Credits: 3
        Result: Connection successful (0x0000)
        Destination CID: 68
        Destination CID: 67
        Destination CID: 66
        Destination CID: 65
        Destination CID: 64

Also make sure the response don't include channels that are not on
BT_CONNECT2 since the chan->ident can be set to the same value as in the
following trace:

< ACL Data TX: Handle 16 flags 0x00 dlen 12
      LE L2CAP: LE Flow Control Credit (0x16) ident 6 len 4
        Source CID: 64
        Credits: 1
...
> ACL Data RX: Handle 16 flags 0x02 dlen 18
      LE L2CAP: Enhanced Credit Connection Request (0x17) ident 6 len 10
        PSM: 39 (0x0027)
        MTU: 517
        MPS: 251
        Credits: 255
        Source CID: 70
< ACL Data TX: Handle 16 flags 0x00 dlen 20
      LE L2CAP: Enhanced Credit Connection Response (0x18) ident 6 len 12
        MTU: 517
        MPS: 247
        Credits: 3
        Result: Connection successful (0x0000)
        Destination CID: 64
        Destination CID: 68

Closes: https://github.com/bluez/bluez/issues/1094
Fixes: 9aa9d9473f15 ("Bluetooth: L2CAP: Fix responding with wrong PDU type")
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
---
 net/bluetooth/l2cap_core.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)
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Patch

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index fec11e576f31..e716bfed4159 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -632,7 +632,8 @@  void __l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
 	    test_bit(FLAG_HOLD_HCI_CONN, &chan->flags))
 		hci_conn_hold(conn->hcon);
 
-	list_add(&chan->list, &conn->chan_l);
+	/* Append to the list since the order matters for ECRED */
+	list_add_tail(&chan->list, &conn->chan_l);
 }
 
 void l2cap_chan_add(struct l2cap_conn *conn, struct l2cap_chan *chan)
@@ -3771,7 +3772,9 @@  static void l2cap_ecred_rsp_defer(struct l2cap_chan *chan, void *data)
 	struct l2cap_ecred_conn_rsp *rsp_flex =
 		container_of(&rsp->pdu.rsp, struct l2cap_ecred_conn_rsp, hdr);
 
-	if (test_bit(FLAG_ECRED_CONN_REQ_SENT, &chan->flags))
+	/* Check if channel is pending */
+	if (chan->state != BT_CONNECT2 ||
+	    test_bit(FLAG_ECRED_CONN_REQ_SENT, &chan->flags))
 		return;
 
 	/* Reset ident so only one response is sent */