On Fri, Mar 1, 2024 at 1:50 PM Luiz Augusto von Dentz
<luiz.dentz@xxxxxxxxx> wrote:
>
> From: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
>
> Attemting to do sock_lock on .recvmsg may cause a deadlock as shown
> bellow, so instead of using sock_sock this uses sk_receive_queue.lock
> on bt_sock_ioctl to avoid the UAF:
>
> INFO: task kworker/u9:1:121 blocked for more than 30 seconds.
> Not tainted 6.7.6-lemon #183
> Workqueue: hci0 hci_rx_work
> Call Trace:
> <TASK>
> __schedule+0x37d/0xa00
> schedule+0x32/0xe0
> __lock_sock+0x68/0xa0
> ? __pfx_autoremove_wake_function+0x10/0x10
> lock_sock_nested+0x43/0x50
> l2cap_sock_recv_cb+0x21/0xa0
> l2cap_recv_frame+0x55b/0x30a0
> ? psi_task_switch+0xeb/0x270
> ? finish_task_switch.isra.0+0x93/0x2a0
> hci_rx_work+0x33a/0x3f0
> process_one_work+0x13a/0x2f0
> worker_thread+0x2f0/0x410
> ? __pfx_worker_thread+0x10/0x10
> kthread+0xe0/0x110
> ? __pfx_kthread+0x10/0x10
> ret_from_fork+0x2c/0x50
> ? __pfx_kthread+0x10/0x10
> ret_from_fork_asm+0x1b/0x30
> </TASK>
>
> Fixes: 2e07e8348ea4 ("Bluetooth: af_bluetooth: Fix Use-After-Free in bt_sock_recvmsg")
> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx>
> ---
> net/bluetooth/af_bluetooth.c | 10 +++-------
> 1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
> index b93464ac3517..67604ccec2f4 100644
> --- a/net/bluetooth/af_bluetooth.c
> +++ b/net/bluetooth/af_bluetooth.c
> @@ -309,14 +309,11 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
> if (flags & MSG_OOB)
> return -EOPNOTSUPP;
>
> - lock_sock(sk);
> -
> skb = skb_recv_datagram(sk, flags, &err);
> if (!skb) {
> if (sk->sk_shutdown & RCV_SHUTDOWN)
> err = 0;
>
> - release_sock(sk);
> return err;
> }
>
> @@ -346,8 +343,6 @@ int bt_sock_recvmsg(struct socket *sock, struct msghdr *msg, size_t len,
>
> skb_free_datagram(sk, skb);
>
> - release_sock(sk);
> -
> if (flags & MSG_TRUNC)
> copied = skblen;
>
> @@ -570,10 +565,11 @@ int bt_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
> if (sk->sk_state == BT_LISTEN)
> return -EINVAL;
>
> - lock_sock(sk);
> + spin_lock(&sk->sk_receive_queue.lock);
> skb = skb_peek(&sk->sk_receive_queue);
> amount = skb ? skb->len : 0;
> - release_sock(sk);
> + spin_unlock(&sk->sk_receive_queue.lock);
> +
> err = put_user(amount, (int __user *)arg);
> break;
>
> --
> 2.43.0
>
--
Luiz Augusto von Dentz
