HCI_UART_PROTO_SET flag is set before hci_uart_set_proto call. If we
receive data from tty layer during this procedure, proto pointer may
not be assigned yet, leading to null pointer dereference in rx method
hci_uart_tty_receive.
This patch fixes this by setting the HCI_UART_PROTO_SET flag once proto
is fully initialized and introduces HCI_UART_PROTO_BUSY flag to avoid
concurrent call to set_proto. We could have fixed this with a mutex as
well.
Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxx>
---
drivers/bluetooth/hci_ldisc.c | 16 +++++++++-------
drivers/bluetooth/hci_uart.h | 1 +
2 files changed, 10 insertions(+), 7 deletions(-)
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index c00168a..fab2641 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -638,6 +638,7 @@ static int hci_uart_set_proto(struct hci_uart *hu, int id)
return err;
hu->proto = p;
+ set_bit(HCI_UART_PROTO_SET, &hu->flags);
err = hci_uart_register_dev(hu);
if (err) {
@@ -692,14 +693,15 @@ static int hci_uart_tty_ioctl(struct tty_struct *tty, struct file *file,
switch (cmd) {
case HCIUARTSETPROTO:
- if (!test_and_set_bit(HCI_UART_PROTO_SET, &hu->flags)) {
- err = hci_uart_set_proto(hu, arg);
- if (err) {
- clear_bit(HCI_UART_PROTO_SET, &hu->flags);
- return err;
- }
- } else
+ if (test_and_set_bit(HCI_UART_PROTO_BUSY, &hu->flags))
return -EBUSY;
+ if (test_bit(HCI_UART_PROTO_SET, &hu->flags))
+ err = -EBUSY;
+ else
+ err = hci_uart_set_proto(hu, arg);
+ clear_bit(HCI_UART_PROTO_BUSY, &hu->flags);
+ if (err)
+ return err;
break;
case HCIUARTGETPROTO:
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index 4814ff0..1a97fa9 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -95,6 +95,7 @@ struct hci_uart {
/* HCI_UART proto flag bits */
#define HCI_UART_PROTO_SET 0
#define HCI_UART_REGISTERED 1
+#define HCI_UART_PROTO_BUSY 2
/* TX states */
#define HCI_UART_SENDING 1
--
1.9.1
--
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