Use tty kref to release the fake tty in usb_console_setup to avoid use
after free if the underlying serial driver has acquired a reference.
Note that using the tty destructor release_one_tty requires some more
state to be initialised.
Fixes: 4a90f09b20f4 ("tty: usb-serial krefs")
Cc: stable <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
---
Changes since v1:
- Use tty_kref_put to release tty also in setup()
- Some more state must be initialised to avoid NULL derefs when the tty
destructor is run after the underlying driver puts its reference.
drivers/usb/serial/console.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/drivers/usb/serial/console.c b/drivers/usb/serial/console.c
index e56f394b58d8..29fa1c3d0089 100644
--- a/drivers/usb/serial/console.c
+++ b/drivers/usb/serial/console.c
@@ -46,6 +46,8 @@ static struct console usbcons;
* ------------------------------------------------------------
*/
+static const struct tty_operations usb_console_fake_tty_ops = {
+};
/*
* The parsing of the command line works exactly like the
@@ -137,14 +139,17 @@ static int usb_console_setup(struct console *co, char *options)
goto reset_open_count;
}
kref_init(&tty->kref);
- tty_port_tty_set(&port->port, tty);
tty->driver = usb_serial_tty_driver;
tty->index = co->index;
init_ldsem(&tty->ldisc_sem);
+ INIT_LIST_HEAD(&tty->tty_files);
+ kref_get(&tty->driver->kref);
+ tty->ops = &usb_console_fake_tty_ops;
if (tty_init_termios(tty)) {
retval = -ENOMEM;
- goto free_tty;
+ goto put_tty;
}
+ tty_port_tty_set(&port->port, tty);
}
/* only call the device specific open if this
@@ -162,7 +167,7 @@ static int usb_console_setup(struct console *co, char *options)
serial->type->set_termios(tty, port, &dummy);
tty_port_tty_set(&port->port, NULL);
- kfree(tty);
+ tty_kref_put(tty);
}
set_bit(ASYNCB_INITIALIZED, &port->port.flags);
}
@@ -178,8 +183,8 @@ static int usb_console_setup(struct console *co, char *options)
fail:
tty_port_tty_set(&port->port, NULL);
- free_tty:
- kfree(tty);
+ put_tty:
+ tty_kref_put(tty);
reset_open_count:
port->port.count = 0;
usb_autopm_put_interface(serial->interface);
--
2.0.5
--
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