4.19-stable review patch. If anyone has any objections, please let me know.
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From: Myungho Jung mhjungk@gmail.com
commit e20a2e9c42c9e4002d9e338d74e7819e88d77162 upstream.
When releasing socket, it is possible to enter hci_sock_release() and hci_sock_dev_event(HCI_DEV_UNREG) at the same time in different thread. The reference count of hdev should be decremented only once from one of them but if storing hdev to local variable in hci_sock_release() before detached from socket and setting to NULL in hci_sock_dev_event(), hci_dev_put(hdev) is unexpectedly called twice. This is resolved by referencing hdev from socket after bt_sock_unlink() in hci_sock_release().
Reported-by: syzbot+fdc00003f4efff43bc5b@syzkaller.appspotmail.com Signed-off-by: Myungho Jung mhjungk@gmail.com Signed-off-by: Marcel Holtmann marcel@holtmann.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- net/bluetooth/hci_sock.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
--- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -831,8 +831,6 @@ static int hci_sock_release(struct socke if (!sk) return 0;
- hdev = hci_pi(sk)->hdev; - switch (hci_pi(sk)->channel) { case HCI_CHANNEL_MONITOR: atomic_dec(&monitor_promisc); @@ -854,6 +852,7 @@ static int hci_sock_release(struct socke
bt_sock_unlink(&hci_sk_list, sk);
+ hdev = hci_pi(sk)->hdev; if (hdev) { if (hci_pi(sk)->channel == HCI_CHANNEL_USER) { /* When releasing a user channel exclusive access,