| Message ID | 20190203005634.GA19908@myunghoj-Precision-5530 |
|---|---|
| State | Awaiting Upstream |
| Delegated to: | David Miller |
| Headers | show |
| Series | Bluetooth: Fix decrementing reference count twice in releasing socket | expand |
Hi Myungho, > 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> > --- > net/bluetooth/hci_sock.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) patch has been applied to bluetooth-next tree. Regards Marcel
diff --git a/net/bluetooth/hci_sock.c b/net/bluetooth/hci_sock.c index 1506e1632394..d4e2a166ae17 100644 --- a/net/bluetooth/hci_sock.c +++ b/net/bluetooth/hci_sock.c @@ -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,
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> --- net/bluetooth/hci_sock.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)