Bluetooth: af_bluetooth: Fix deadlock

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@intel.com>

diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c
index b93464ac3517f4128ae1af4b35f7253f1d769e1f..67604ccec2f42739a554bc93d7834ebc4177589c 100644 (file)
--- 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;