linux-kernel - Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap

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Message-ID: <tencent_6352E6C65F89856EFC6EC18C92E7CCC6FF06@qq.com>
Date: Sun,  8 Sep 2024 12:07:21 +0800
From: Edward Adam Davis <eadavis@...com>
To: syzbot+c12e2f941af1feb5632c@...kaller.appspotmail.com
Cc: linux-kernel@...r.kernel.org,
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [bluetooth?] KASAN: slab-use-after-free Read in l2cap_connect (2)

after release conn, we need to cancle rx_work

#syz test

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index f25a21f532aa..4f7b45bb863f 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3776,18 +3776,19 @@ static void hci_acldata_packet(struct hci_dev *hdev, struct sk_buff *skb)
 
 	hci_dev_lock(hdev);
 	conn = hci_conn_hash_lookup_handle(hdev, handle);
-	hci_dev_unlock(hdev);
 
 	if (conn) {
 		hci_conn_enter_active_mode(conn, BT_POWER_FORCE_ACTIVE_OFF);
 
 		/* Send to upper protocol */
 		l2cap_recv_acldata(conn, skb, flags);
+		hci_dev_unlock(hdev);
 		return;
 	} else {
 		bt_dev_err(hdev, "ACL packet for unknown connection handle %d",
 			   handle);
 	}
+	hci_dev_unlock(hdev);
 
 	kfree_skb(skb);
 }
diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index 9988ba382b68..b948b0a3b2f2 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -4072,10 +4072,8 @@ static int l2cap_connect_req(struct l2cap_conn *conn,
 	if (cmd_len < sizeof(struct l2cap_conn_req))
 		return -EPROTO;
 
-	hci_dev_lock(hdev);
 	if (hci_dev_test_flag(hdev, HCI_MGMT))
 		mgmt_device_connected(hdev, hcon, NULL, 0);
-	hci_dev_unlock(hdev);
 
 	l2cap_connect(conn, cmd, data, L2CAP_CONN_RSP);
 	return 0;