From f3ff53065caf9ed9fe1003eb50d392310dbbac1b Mon Sep 17 00:00:00 2001 From: "Lee, Chun-Yi" <joeyli.kernel@gmail.com> Date: Mon, 10 Jul 2023 23:17:23 +0800 Subject: [PATCH] Bluetooth: hci_ldisc: check HCI_UART_PROTO_READY flag in HCIUARTGETPROTO 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@ucr.edu> Closes: https://lore.kernel.org/all/CA+UBctC3p49aTgzbVgkSZ2+TQcqq4fPDO7yZitFT5uBPDeCO2g@mail.gmail.com/ [1] Reported-by: Weiteng Chen <wchen130@ucr.edu> Closes: https://lore.kernel.org/lkml/CA+UBctDPEvHdkHMwD340=n02rh+jNRJNNQ5LBZNA+Wm4Keh2ow@mail.gmail.com/T/ [2] Signed-off-by: "Lee, Chun-Yi" <jlee@suse.com> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Harshit Mogalapalli <harshit.m.mogalapalli@oracle.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/bluetooth/hci_ldisc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c index 726d5c83c..e7d78937f 100755 --- a/drivers/bluetooth/hci_ldisc.c +++ b/drivers/bluetooth/hci_ldisc.c @@ -768,7 +768,8 @@ static int hci_uart_tty_ioctl(struct tty_struct *tty, struct file *file, 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;