tty_set_termios() has the following WARMN_ON which can be triggered with a
syscall to invoke TIOCGETD __NR_ioctl.
WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER);
Reference: https://syzkaller.appspot.com/bug?id=2410d22f1d8e5984217329dd0884b01d99e3e48d
A simple change would have been to print error message instead of WARN_ON.
However, the callers assume that tty_set_termios() always returns 0 and
don't check return value. The complete solution is fixing all the callers
to check error and bail out to fix the WARN_ON.
This fix changes tty_set_termios() to return error and all the callers
to check error and bail out. The reproducer is used to reproduce the
problem and verify the fix.
Reported-by: syzbot+a950165cbb86bdd023a4@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Shuah Khan <shuah@xxxxxxxxxx>
---
drivers/bluetooth/hci_ldisc.c | 8 ++++++--
drivers/staging/speakup/spk_ttyio.c | 4 +++-
drivers/tty/serdev/serdev-ttyport.c | 20 +++++++++++++++-----
drivers/tty/tty_ioctl.c | 14 ++++++++++----
net/nfc/nci/uart.c | 1 +
5 files changed, 35 insertions(+), 12 deletions(-)
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index fbf7b4df23ab..643c4c75f86d 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -321,6 +321,8 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
status = tty_set_termios(tty, &ktermios);
BT_DBG("Disabling hardware flow control: %s",
status ? "failed" : "success");
+ if (status)
+ return;
/* Clear RTS to prevent the device from sending */
/* Most UARTs need OUT2 to enable interrupts */
@@ -369,13 +371,15 @@ void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
{
struct tty_struct *tty = hu->tty;
struct ktermios ktermios;
+ int ret;
ktermios = tty->termios;
ktermios.c_cflag &= ~CBAUD;
tty_termios_encode_baud_rate(&ktermios, speed, speed);
- /* tty_set_termios() return not checked as it is always 0 */
- tty_set_termios(tty, &ktermios);
+ ret = tty_set_termios(tty, &ktermios);
+ if (ret)
+ return;
BT_DBG("%s: New tty speeds: %d/%d", hu->hdev->name,
tty->termios.c_ispeed, tty->termios.c_ospeed);
diff --git a/drivers/staging/speakup/spk_ttyio.c b/drivers/staging/speakup/spk_ttyio.c
index c92bbd05516e..ded6f8089fc8 100644
--- a/drivers/staging/speakup/spk_ttyio.c
+++ b/drivers/staging/speakup/spk_ttyio.c
@@ -165,7 +165,9 @@ static int spk_ttyio_initialise_ldisc(struct spk_synth *synth)
get_termios(tty, &tmp_termios);
if (!(tmp_termios.c_cflag & CRTSCTS)) {
tmp_termios.c_cflag |= CRTSCTS;
- tty_set_termios(tty, &tmp_termios);
+ ret = tty_set_termios(tty, &tmp_termios);
+ if (ret)
+ return ret;
/*
* check c_cflag to see if it's updated as tty_set_termios may not return
* error even when no tty bits are changed by the request.
diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serdev-ttyport.c
index fa1672993b4c..29b51370deac 100644
--- a/drivers/tty/serdev/serdev-ttyport.c
+++ b/drivers/tty/serdev/serdev-ttyport.c
@@ -136,7 +136,9 @@ static int ttyport_open(struct serdev_controller *ctrl)
ktermios.c_cflag |= CRTSCTS;
/* Hangups are not supported so make sure to ignore carrier detect. */
ktermios.c_cflag |= CLOCAL;
- tty_set_termios(tty, &ktermios);
+ ret = tty_set_termios(tty, &ktermios);
+ if (ret)
+ return ret;
set_bit(SERPORT_ACTIVE, &serport->flags);
@@ -171,12 +173,14 @@ static unsigned int ttyport_set_baudrate(struct serdev_controller *ctrl, unsigne
struct serport *serport = serdev_controller_get_drvdata(ctrl);
struct tty_struct *tty = serport->tty;
struct ktermios ktermios = tty->termios;
+ int retval;
ktermios.c_cflag &= ~CBAUD;
tty_termios_encode_baud_rate(&ktermios, speed, speed);
- /* tty_set_termios() return not checked as it is always 0 */
- tty_set_termios(tty, &ktermios);
+ retval = tty_set_termios(tty, &ktermios);
+ if (retval)
+ return retval;
return ktermios.c_ospeed;
}
@@ -185,13 +189,16 @@ static void ttyport_set_flow_control(struct serdev_controller *ctrl, bool enable
struct serport *serport = serdev_controller_get_drvdata(ctrl);
struct tty_struct *tty = serport->tty;
struct ktermios ktermios = tty->termios;
+ int retval;
if (enable)
ktermios.c_cflag |= CRTSCTS;
else
ktermios.c_cflag &= ~CRTSCTS;
- tty_set_termios(tty, &ktermios);
+ retval = tty_set_termios(tty, &ktermios);
+ if (retval)
+ return;
}
static int ttyport_set_parity(struct serdev_controller *ctrl,
@@ -200,6 +207,7 @@ static int ttyport_set_parity(struct serdev_controller *ctrl,
struct serport *serport = serdev_controller_get_drvdata(ctrl);
struct tty_struct *tty = serport->tty;
struct ktermios ktermios = tty->termios;
+ int retval;
ktermios.c_cflag &= ~(PARENB | PARODD | CMSPAR);
if (parity != SERDEV_PARITY_NONE) {
@@ -208,7 +216,9 @@ static int ttyport_set_parity(struct serdev_controller *ctrl,
ktermios.c_cflag |= PARODD;
}
- tty_set_termios(tty, &ktermios);
+ retval = tty_set_termios(tty, &ktermios);
+ if (retval)
+ return retval;
if ((tty->termios.c_cflag & (PARENB | PARODD | CMSPAR)) !=
(ktermios.c_cflag & (PARENB | PARODD | CMSPAR)))
diff --git a/drivers/tty/tty_ioctl.c b/drivers/tty/tty_ioctl.c
index 9245fffdbceb..93e6531573ad 100644
--- a/drivers/tty/tty_ioctl.c
+++ b/drivers/tty/tty_ioctl.c
@@ -316,8 +316,9 @@ int tty_set_termios(struct tty_struct *tty, struct ktermios *new_termios)
struct ktermios old_termios;
struct tty_ldisc *ld;
- WARN_ON(tty->driver->type == TTY_DRIVER_TYPE_PTY &&
- tty->driver->subtype == PTY_TYPE_MASTER);
+ if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
+ tty->driver->subtype == PTY_TYPE_MASTER)
+ return -EINVAL;
/*
* Perform the actual termios internal changes under lock.
*/
@@ -411,7 +412,9 @@ static int set_termios(struct tty_struct *tty, void __user *arg, int opt)
return -ERESTARTSYS;
}
- tty_set_termios(tty, &tmp_termios);
+ retval = tty_set_termios(tty, &tmp_termios);
+ if (retval)
+ return retval;
/* FIXME: Arguably if tmp_termios == tty->termios AND the
actual requested termios was not tmp_termios then we may
@@ -588,7 +591,10 @@ static int set_sgttyb(struct tty_struct *tty, struct sgttyb __user *sgttyb)
termios.c_ospeed);
#endif
up_write(&tty->termios_rwsem);
- tty_set_termios(tty, &termios);
+ retval = tty_set_termios(tty, &termios);
+ if (retval)
+ return retval;
+
return 0;
}
#endif
diff --git a/net/nfc/nci/uart.c b/net/nfc/nci/uart.c
index 78fe622eba65..9978c21ce34d 100644
--- a/net/nfc/nci/uart.c
+++ b/net/nfc/nci/uart.c
@@ -447,6 +447,7 @@ void nci_uart_set_config(struct nci_uart *nu, int baudrate, int flow_ctrl)
else
new_termios.c_cflag &= ~CRTSCTS;
+ /* FIXME tty_set_termios() could return error */
tty_set_termios(nu->tty, &new_termios);
}
EXPORT_SYMBOL_GPL(nci_uart_set_config);
--
2.17.1
