From 4f42363c814f28fe3f59847c35acf1ed033bedd4 Mon Sep 17 00:00:00 2001 From: Dudu Lu Date: Wed, 15 Apr 2026 18:43:55 +0800 Subject: Bluetooth: l2cap: fix MPS check in l2cap_ecred_reconf_req The L2CAP specification states that if more than one channel is being reconfigured, the MPS shall not be decreased. The current check has two issues: 1) The comparison uses >= (greater-than-or-equal), which incorrectly rejects reconfiguration requests where the MPS stays the same. Since the spec says MPS "shall be greater than or equal to the current MPS", only a strict decrease (remote_mps > mps) should be rejected. Keeping the same MPS is valid. 2) The multi-channel guard uses `&& i` (loop index) to approximate "more than one channel", but this incorrectly allows MPS decrease for the first channel (i==0) even when multiple channels are being reconfigured. Replace with `&& num_scid > 1` which correctly checks whether the request covers more than one channel. Fixes: 7accb1c4321a ("Bluetooth: L2CAP: Fix invalid response to L2CAP_ECRED_RECONF_REQ") Signed-off-by: Dudu Lu Signed-off-by: Luiz Augusto von Dentz --- net/bluetooth/l2cap_core.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c index 77dec104a9c3..b15374b951fa 100644 --- a/net/bluetooth/l2cap_core.c +++ b/net/bluetooth/l2cap_core.c @@ -5428,7 +5428,7 @@ static inline int l2cap_ecred_reconf_req(struct l2cap_conn *conn, * configured, the MPS field may be less than the current MPS * of that channel. */ - if (chan[i]->remote_mps >= mps && i) { + if (chan[i]->remote_mps > mps && num_scid > 1) { BT_ERR("chan %p decreased MPS %u -> %u", chan[i], chan[i]->remote_mps, mps); result = L2CAP_RECONF_INVALID_MPS; -- cgit v1.2.3