From: Johan Hovold johan@kernel.org
commit dc8c8437658667be9b11ec25c4b5482ed2becdaa upstream.
Changing the port close delay or type are privileged operations so make sure to return -EPERM if a regular user tries to change them.
Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold johan@kernel.org Link: https://lore.kernel.org/r/20210407102334.32361-12-johan@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/tty/moxa.c | 16 +++++++++++----- 1 file changed, 11 insertions(+), 5 deletions(-)
--- a/drivers/tty/moxa.c +++ b/drivers/tty/moxa.c @@ -2050,6 +2050,7 @@ static int moxa_set_serial_info(struct t struct serial_struct *ss) { struct moxa_port *info = tty->driver_data; + unsigned int close_delay;
if (tty->index == MAX_PORTS) return -EINVAL; @@ -2061,19 +2062,24 @@ static int moxa_set_serial_info(struct t ss->baud_base != 921600) return -EPERM;
+ close_delay = msecs_to_jiffies(ss->close_delay * 10); + mutex_lock(&info->port.mutex); if (!capable(CAP_SYS_ADMIN)) { - if (((ss->flags & ~ASYNC_USR_MASK) != + if (close_delay != info->port.close_delay || + ss->type != info->type || + ((ss->flags & ~ASYNC_USR_MASK) != (info->port.flags & ~ASYNC_USR_MASK))) { mutex_unlock(&info->port.mutex); return -EPERM; } - } - info->port.close_delay = msecs_to_jiffies(ss->close_delay * 10); + } else { + info->port.close_delay = close_delay;
- MoxaSetFifo(info, ss->type == PORT_16550A); + MoxaSetFifo(info, ss->type == PORT_16550A);
- info->type = ss->type; + info->type = ss->type; + } mutex_unlock(&info->port.mutex); return 0; }