Commit 6ea83d93 authored by Jeremy Cline's avatar Jeremy Cline Committed by Greg Kroah-Hartman

Bluetooth: hci_ldisc: Initialize hci_dev before open()

commit 32a7b4cbe93b0a0ef7e63d31ca69ce54736c4412 upstream.

The hci_dev struct hdev is referenced in work queues and timers started
by open() in some protocols. This creates a race between the
initialization function and the work or timer which can result hdev
being dereferenced while it is still null.

The syzbot report contains a reliable reproducer which causes a null
pointer dereference of hdev in hci_uart_write_work() by making the
memory allocation for hdev fail.

To fix this, ensure hdev is valid from before calling a protocol's
open() until after calling a protocol's close().

Reported-by: syzbot+257790c15bcdef6fe00c@syzkaller.appspotmail.com
Signed-off-by: 's avatarJeremy Cline <jcline@redhat.com>
Signed-off-by: 's avatarMarcel Holtmann <marcel@holtmann.org>
Signed-off-by: 's avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 3df00eb8
......@@ -207,11 +207,11 @@ static void hci_uart_init_work(struct work_struct *work)
err = hci_register_dev(hu->hdev);
if (err < 0) {
BT_ERR("Can't register HCI device");
clear_bit(HCI_UART_PROTO_READY, &hu->flags);
hu->proto->close(hu);
hdev = hu->hdev;
hu->hdev = NULL;
hci_free_dev(hdev);
clear_bit(HCI_UART_PROTO_READY, &hu->flags);
hu->proto->close(hu);
return;
}
......@@ -612,6 +612,7 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
static int hci_uart_register_dev(struct hci_uart *hu)
{
struct hci_dev *hdev;
int err;
BT_DBG("");
......@@ -655,11 +656,22 @@ static int hci_uart_register_dev(struct hci_uart *hu)
else
hdev->dev_type = HCI_PRIMARY;
/* Only call open() for the protocol after hdev is fully initialized as
* open() (or a timer/workqueue it starts) may attempt to reference it.
*/
err = hu->proto->open(hu);
if (err) {
hu->hdev = NULL;
hci_free_dev(hdev);
return err;
}
if (test_bit(HCI_UART_INIT_PENDING, &hu->hdev_flags))
return 0;
if (hci_register_dev(hdev) < 0) {
BT_ERR("Can't register HCI device");
hu->proto->close(hu);
hu->hdev = NULL;
hci_free_dev(hdev);
return -ENODEV;
......@@ -679,17 +691,12 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
if (!p)
return -EPROTONOSUPPORT;
err = p->open(hu);
if (err)
return err;
hu->proto = p;
set_bit(HCI_UART_PROTO_READY, &hu->flags);
err = hci_uart_register_dev(hu);
if (err) {
clear_bit(HCI_UART_PROTO_READY, &hu->flags);
p->close(hu);
return err;
}
......
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