Bluetooth: Fix locking in bt_accept_enqueue() for BH context

With commit e16337622016 ("Bluetooth: Handle bt_accept_enqueue() socket
atomically") lock_sock[_nested]() is used to acquire the socket lock
before manipulating the socket. lock_sock[_nested]() may block, which
is problematic since bt_accept_enqueue() can be called in bottom half
context (e.g. from rfcomm_connect_ind()):

[<ffffff80080d81ec>] __might_sleep+0x4c/0x80
[<ffffff800876c7b0>] lock_sock_nested+0x24/0x58
[<ffffff8000d7c27c>] bt_accept_enqueue+0x48/0xd4 [bluetooth]
[<ffffff8000e67d8c>] rfcomm_connect_ind+0x190/0x218 [rfcomm]

Add a parameter to bt_accept_enqueue() to indicate whether the
function is called from BH context, and acquire the socket lock
with bh_lock_sock_nested() if that's the case.

Also adapt all callers of bt_accept_enqueue() to pass the new
parameter:

- l2cap_sock_new_connection_cb()
  - uses lock_sock() to lock the parent socket => process context

- rfcomm_connect_ind()
  - acquires the parent socket lock with bh_lock_sock() => BH
    context

- __sco_chan_add()
  - called from sco_chan_add(), which is called from sco_connect().
    parent is NULL, hence bt_accept_enqueue() isn't called in this
    code path and we can ignore it
  - also called from sco_conn_ready(). uses bh_lock_sock() to acquire
    the parent lock => BH context

Fixes: e16337622016 ("Bluetooth: Handle bt_accept_enqueue() socket atomically")
Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Cc: stable@vger.kernel.org

1 files changed, 1 insertions, 1 deletions

diff --git a/include/net/bluetooth/bluetooth.h b/include/net/bluetooth/bluetooth.h
index ec9d6bc65855..fabee6db0abb 100644
--- a/include/net/bluetooth/bluetooth.h
+++ b/include/net/bluetooth/bluetooth.h
@@ -276,7 +276,7 @@ int  bt_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg);
 int  bt_sock_wait_state(struct sock *sk, int state, unsigned long timeo);
 int  bt_sock_wait_ready(struct sock *sk, unsigned long flags);
 
-void bt_accept_enqueue(struct sock *parent, struct sock *sk);
+void bt_accept_enqueue(struct sock *parent, struct sock *sk, bool bh);
 void bt_accept_unlink(struct sock *sk);
 struct sock *bt_accept_dequeue(struct sock *parent, struct socket *newsock);