4.14-stable review patch. If anyone has any objections, please let me know.
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From: Jeremy Cline jcline@redhat.com
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: Jeremy Cline jcline@redhat.com Signed-off-by: Marcel Holtmann marcel@holtmann.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/bluetooth/hci_ldisc.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-)
--- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -207,11 +207,11 @@ static void hci_uart_init_work(struct wo 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 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 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 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; }