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Bluetooth: Fix decrementing reference count twice in releasing socket 

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>
This commit is contained in:
Myungho Jung 2019-02-02 16:56:36 -08:00 committed by Marcel Holtmann
parent 017a01ccfb
commit e20a2e9c42
1 changed files with 1 additions and 2 deletions
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3
net/bluetooth/hci_sock.c
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@ -831,8 +831,6 @@ static int hci_sock_release(struct socket *sock)
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 socket *sock)
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,