[PATCH] Bluetooth: L2CAP: Add missing checks for invalid DCID

[PATCH] Bluetooth: L2CAP: Add missing checks for invalid DCID

[Sungwoo Kim]

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 ("L2CAP: Add missing checks for invalid LE DCID")
Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
---
 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 376b523c7..104eb0320 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4306,6 +4306,10 @@ 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);
 
@@ -4337,6 +4341,11 @@ 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;
-- 
2.34.1

Re: [PATCH] Bluetooth: L2CAP: Add missing checks for invalid DCID

[patchwork-bot+bluetooth]

Hello:

This patch was applied to bluetooth/bluetooth-next.git (master)
by Luiz Augusto von Dentz <luiz.von.dentz@intel.com>:

On Sat,  3 Jun 2023 08:28:09 -0400 you wrote:
> 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 ("L2CAP: Add missing checks for invalid LE DCID")
> Signed-off-by: Sungwoo Kim <iam@sung-woo.kim>
> 
> [...]

Here is the summary with links:
  - Bluetooth: L2CAP: Add missing checks for invalid DCID
    https://git.kernel.org/bluetooth/bluetooth-next/c/f9367ce74db3

You are awesome, thank you!
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