linux-kernel - [PATCH] Bluetooth: hci_sock: purge socket queues in the destruct() callback

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Date:   Fri,  8 Oct 2021 03:04:24 +0800
From:   Nguyen Dinh Phi <phind.uet@...il.com>
To:     marcel@...tmann.org, johan.hedberg@...il.com, luiz.dentz@...il.com,
        davem@...emloft.net, kuba@...nel.org
Cc:     linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        syzbot+4c4ffd1e1094dae61035@...kaller.appspotmail.com
Subject: [PATCH] Bluetooth: hci_sock: purge socket queues in the destruct() callback

The receive path may take the socket right before hci_sock_release(),
but it may enqueue the packets to the socket queues after the call to
skb_queue_purge(), therefore the socket can be destroyed without clear
its queues completely.

Moving these skb_queue_purge() to the hci_sock_destruct() will fix this
issue, because nothing is referencing the socket at this point.

Signed-off-by: Nguyen Dinh Phi <phind.uet@...il.com>
Reported-by: syzbot+4c4ffd1e1094dae61035@...kaller.appspotmail.com
---
 net/bluetooth/hci_sock.c | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c
index d0dad1fafe07..446573a12571 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -889,10 +889,6 @@ static int hci_sock_release(struct socket *sock)
 	}
 
 	sock_orphan(sk);
-
-	skb_queue_purge(&sk->sk_receive_queue);
-	skb_queue_purge(&sk->sk_write_queue);
-
 	release_sock(sk);
 	sock_put(sk);
 	return 0;
@@ -2058,6 +2054,12 @@ static int hci_sock_getsockopt(struct socket *sock, int level, int optname,
 	return err;
 }
 
+static void hci_sock_destruct(struct sock *sk)
+{
+	skb_queue_purge(&sk->sk_receive_queue);
+	skb_queue_purge(&sk->sk_write_queue);
+}
+
 static const struct proto_ops hci_sock_ops = {
 	.family		= PF_BLUETOOTH,
 	.owner		= THIS_MODULE,
@@ -2111,6 +2113,7 @@ static int hci_sock_create(struct net *net, struct socket *sock, int protocol,
 
 	sock->state = SS_UNCONNECTED;
 	sk->sk_state = BT_OPEN;
+	sk->sk_destruct = hci_sock_destruct;
 
 	bt_sock_link(&hci_sk_list, sk);
 	return 0;
-- 
2.25.1