netdev - [PATCH] Bluetooth: Free potentially unfreed SCO connection

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Message-ID: <20230203173024.1.Ieb6662276f3bd3d79e9134ab04523d584c300c45@changeid>
Date:   Fri,  3 Feb 2023 17:30:55 +0800
From:   Archie Pusaka <apusaka@...gle.com>
To:     linux-bluetooth <linux-bluetooth@...r.kernel.org>,
        Luiz Augusto von Dentz <luiz.dentz@...il.com>,
        Marcel Holtmann <marcel@...tmann.org>
Cc:     CrosBT Upstreaming <chromeos-bluetooth-upstreaming@...omium.org>,
        Archie Pusaka <apusaka@...omium.org>,
        Ying Hsu <yinghsu@...omium.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        Paolo Abeni <pabeni@...hat.com>, linux-kernel@...r.kernel.org,
        netdev@...r.kernel.org
Subject: [PATCH] Bluetooth: Free potentially unfreed SCO connection

From: Archie Pusaka <apusaka@...omium.org>

It is possible to initiate a SCO connection while deleting the
corresponding ACL connection, e.g. in below scenario:

(1) < hci setup sync connect command
(2) > hci disconn complete event (for the acl connection)
(3) > hci command complete event (for(1), failure)

When it happens, hci_cs_setup_sync_conn won't be able to obtain the
reference to the SCO connection, so it will be stuck and potentially
hinder subsequent connections to the same device.

This patch prevents that by also deleting the SCO connection if it is
still not established when the corresponding ACL connection is deleted.

Signed-off-by: Archie Pusaka <apusaka@...omium.org>
Reviewed-by: Ying Hsu <yinghsu@...omium.org>

---

 net/bluetooth/hci_conn.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/bluetooth/hci_conn.c b/net/bluetooth/hci_conn.c
index 61a34801e61e..838f51c272a6 100644
--- a/net/bluetooth/hci_conn.c
+++ b/net/bluetooth/hci_conn.c
@@ -1061,8 +1061,15 @@ int hci_conn_del(struct hci_conn *conn)
 
 	if (conn->type == ACL_LINK) {
 		struct hci_conn *sco = conn->link;
-		if (sco)
+		if (sco) {
 			sco->link = NULL;
+			/* Due to race, SCO connection might be not established
+			 * yet at this point. Delete it now, otherwise it is
+			 * possible for it to be stuck and can't be deleted.
+			 */
+			if (sco->handle == HCI_CONN_HANDLE_UNSET)
+				hci_conn_del(sco);
+		}
 
 		/* Unacked frames */
 		hdev->acl_cnt += conn->sent;
-- 
2.39.1.519.gcb327c4b5f-goog