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staging: fwserial: fix TIOCSSERIAL permission check 

commit 2104eb283df66a482b60254299acbe3c68c03412 upstream.

Changing the port close-delay parameter is a privileged operation so
make sure to return -EPERM if a regular user tries to change it.

Fixes: 7355ba3445 ("staging: fwserial: Add TTY-over-Firewire serial driver")
Cc: stable@vger.kernel.org      # 3.8
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407102334.32361-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2021-04-07 12:23:20 +02:00 committed by Greg Kroah-Hartman
parent ebb46274e3
commit 66ca71d283
1 changed files with 6 additions and 2 deletions
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8
drivers/staging/fwserial/fwserial.c
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@ -1232,20 +1232,24 @@ static int set_serial_info(struct tty_struct *tty,
struct serial_struct *ss)
{
struct fwtty_port *port = tty->driver_data;
unsigned int cdelay;
if (ss->irq != 0 || ss->port != 0 || ss->custom_divisor != 0 ||
ss->baud_base != 400000000)
return -EPERM;
cdelay = msecs_to_jiffies(ss->close_delay * 10);
mutex_lock(&port->port.mutex);
if (!capable(CAP_SYS_ADMIN)) {
if (((ss->flags & ~ASYNC_USR_MASK) !=
if (cdelay != port->port.close_delay ||
((ss->flags & ~ASYNC_USR_MASK) !=
(port->port.flags & ~ASYNC_USR_MASK))) {
mutex_unlock(&port->port.mutex);
return -EPERM;
}
}
port->port.close_delay = msecs_to_jiffies(ss->close_delay * 10);
port->port.close_delay = cdelay;
mutex_unlock(&port->port.mutex);
return 0;