From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthias Kaehlcke Subject: [PATCH] Bluetooth: Fix locking in bt_accept_enqueue() for BH context Date: Mon, 15 Oct 2018 15:39:10 -0700 Message-ID: <20181015223910.197729-1-mka@chromium.org> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: linux-bluetooth@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Konstantin Khlebnikov , Balakrishna Godavarthi , Douglas Anderson , Dmitry Grinberg , Matthias Kaehlcke To: Marcel Holtmann , Johan Hedberg , "David S . Miller" , Dean Jenkins Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org 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()). The socket API provides bh_lock_sock[_nested]() to acquire the socket lock in bottom half context. Check the context in bt_accept_enqueue() and use the appropriate locking mechanism for the context. Fixes: e16337622016 ("Bluetooth: Handle bt_accept_enqueue() socket atomically") Signed-off-by: Matthias Kaehlcke --- Not sure if this is the correct solution, it's certainly not elegant and checkpatch.pl complains that in_atomic() shouldn't be used outside of core kernel code. I'm open to other suggestions :) net/bluetooth/af_bluetooth.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-) diff --git a/net/bluetooth/af_bluetooth.c b/net/bluetooth/af_bluetooth.c index deacc52d7ff1..0f0540dbb44a 100644 --- a/net/bluetooth/af_bluetooth.c +++ b/net/bluetooth/af_bluetooth.c @@ -159,10 +159,20 @@ void bt_accept_enqueue(struct sock *parent, struct sock *sk) BT_DBG("parent %p, sk %p", parent, sk); sock_hold(sk); - lock_sock_nested(sk, SINGLE_DEPTH_NESTING); + + if (in_atomic()) + bh_lock_sock_nested(sk); + else + lock_sock_nested(sk, SINGLE_DEPTH_NESTING); + list_add_tail(&bt_sk(sk)->accept_q, &bt_sk(parent)->accept_q); bt_sk(sk)->parent = parent; - release_sock(sk); + + if (in_atomic()) + bh_unlock_sock(sk); + else + release_sock(sk); + parent->sk_ack_backlog++; } EXPORT_SYMBOL(bt_accept_enqueue); -- 2.19.1.331.ge82ca0e54c-goog