From b91cfb2573aeb5ab426fc3c35bcfe9e0d2a7ecbc Mon Sep 17 00:00:00 2001 From: Johan Hovold Date: Wed, 7 Apr 2021 12:23:32 +0200 Subject: [PATCH] tty: mxser: fix TIOCSSERIAL permission check Changing the port type and closing_wait parameter are privileged operations so make sure to return -EPERM if a regular user tries to change them. Note that the closing_wait parameter would not actually have been changed but the return value did not indicate that. Cc: stable@vger.kernel.org Signed-off-by: Johan Hovold Link: https://lore.kernel.org/r/20210407102334.32361-15-johan@kernel.org Signed-off-by: Greg Kroah-Hartman --- drivers/tty/mxser.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c index 914b23071961..2d8e76263a25 100644 --- a/drivers/tty/mxser.c +++ b/drivers/tty/mxser.c @@ -1270,6 +1270,7 @@ static int mxser_set_serial_info(struct tty_struct *tty, if (!capable(CAP_SYS_ADMIN)) { if ((ss->baud_base != info->baud_base) || (close_delay != info->port.close_delay) || + (closing_wait != info->port.closing_wait) || ((ss->flags & ~ASYNC_USR_MASK) != (info->port.flags & ~ASYNC_USR_MASK))) { mutex_unlock(&port->mutex); return -EPERM; @@ -1296,12 +1297,12 @@ static int mxser_set_serial_info(struct tty_struct *tty, baud = ss->baud_base / ss->custom_divisor; tty_encode_baud_rate(tty, baud, baud); } + + info->type = ss->type; + + process_txrx_fifo(info); } - info->type = ss->type; - - process_txrx_fifo(info); - if (tty_port_initialized(port)) { if (flags != (port->flags & ASYNC_SPD_MASK)) { spin_lock_irqsave(&info->slock, sl_flags);