[PATCH 4.14/4.19/5.4/5.10/5.15 0/1] Bluetooth: hci_sock: purge socket queues in the destruct() callback

[PATCH 4.14/4.19/5.4/5.10/5.15 0/1] Bluetooth: hci_sock: purge socket queues in the destruct() callback

[Fedor Pchelkin]

Syzkaller reports a memory leak in mgmt_cmd_complete(). The issue can be
triggered on 4.14/4.19/5.4/5.10/5.15 stable branches. The following fixing
patch can be cleanly applied to them.

[PATCH 4.14/4.19/5.4/5.10/5.15 1/1] Bluetooth: hci_sock: purge socket queues in the destruct() callback

[Fedor Pchelkin]

From: Nguyen Dinh Phi <phind.uet@gmail.com>

commit 709fca500067524381e28a5f481882930eebac88 upstream.

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@gmail.com>
Reported-by: syzbot+4c4ffd1e1094dae61035@syzkaller.appspotmail.com
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
---
 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 f1128c2134f0..3f92a21cabe8 100644
--- a/net/bluetooth/hci_sock.c
+++ b/net/bluetooth/hci_sock.c
@@ -888,10 +888,6 @@ 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;
@@ -2012,6 +2008,12 @@ 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,
@@ -2065,6 +2067,7 @@ 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;
-- 
2.34.1

Re: [PATCH 4.14/4.19/5.4/5.10/5.15 1/1] Bluetooth: hci_sock: purge socket queues in the destruct() callback

[Greg Kroah-Hartman]

On Thu, Mar 09, 2023 at 09:12:51PM +0300, Fedor Pchelkin wrote:
> From: Nguyen Dinh Phi <phind.uet@gmail.com>
> 
> commit 709fca500067524381e28a5f481882930eebac88 upstream.
> 
> 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@gmail.com>
> Reported-by: syzbot+4c4ffd1e1094dae61035@syzkaller.appspotmail.com
> Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
> Signed-off-by: Fedor Pchelkin <pchelkin@ispras.ru>
> ---
>  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 f1128c2134f0..3f92a21cabe8 100644
> --- a/net/bluetooth/hci_sock.c
> +++ b/net/bluetooth/hci_sock.c
> @@ -888,10 +888,6 @@ 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;
> @@ -2012,6 +2008,12 @@ 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,
> @@ -2065,6 +2067,7 @@ 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;
> -- 
> 2.34.1
> 

Now queued up, thanks.

greg k-h