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Bluetooth: hci_ldisc: Initialize hci_dev before open()

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commit 32a7b4cbe9 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: Jeremy Cline <jcline@redhat.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jeremy Cline
2019-02-06 12:54:16 -05:00
committed by Greg Kroah-Hartman
parent 3df00eb895
commit 6ea83d9338
1 changed files with 14 additions and 7 deletions
Download Patch File Download Diff File Expand all files Collapse all files

21
drivers/bluetooth/hci_ldisc.c
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@@ -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;
}