5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Lee, Chun-Yi <joeyli.kernel@xxxxxxxxx> commit 9c33663af9ad115f90c076a1828129a3fbadea98 upstream. This patch adds code to check HCI_UART_PROTO_READY flag before accessing hci_uart->proto. It fixes the race condition in hci_uart_tty_ioctl() between HCIUARTSETPROTO and HCIUARTGETPROTO. This issue bug found by Yu Hao and Weiteng Chen: BUG: general protection fault in hci_uart_tty_ioctl [1] The information of C reproducer can also reference the link [2] Reported-by: Yu Hao <yhao016@xxxxxxx> Closes: https://lore.kernel.org/all/CA+UBctC3p49aTgzbVgkSZ2+TQcqq4fPDO7yZitFT5uBPDeCO2g@xxxxxxxxxxxxxx/ [1] Reported-by: Weiteng Chen <wchen130@xxxxxxx> Closes: https://lore.kernel.org/lkml/CA+UBctDPEvHdkHMwD340=n02rh+jNRJNNQ5LBZNA+Wm4Keh2ow@xxxxxxxxxxxxxx/T/ [2] Signed-off-by: "Lee, Chun-Yi" <jlee@xxxxxxxx> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@xxxxxxxxx> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/bluetooth/hci_ldisc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -765,7 +765,8 @@ static int hci_uart_tty_ioctl(struct tty break; case HCIUARTGETPROTO: - if (test_bit(HCI_UART_PROTO_SET, &hu->flags)) + if (test_bit(HCI_UART_PROTO_SET, &hu->flags) && + test_bit(HCI_UART_PROTO_READY, &hu->flags)) err = hu->proto->id; else err = -EUNATCH;
