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tty: moxa: fix TIOCSSERIAL permission check

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commit dc8c843765 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>
This commit is contained in:
Johan Hovold 2021-04-07 12:23:29 +02:00 committed by Greg Kroah-Hartman
parent 6096118089
commit af5145c8ef
1 changed files with 12 additions and 6 deletions
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12
drivers/tty/moxa.c
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@ -2050,6 +2050,7 @@ static int moxa_set_serial_info(struct tty_struct *tty,
struct serial_struct *ss) struct serial_struct *ss)
{ {
struct moxa_port *info = tty->driver_data; struct moxa_port *info = tty->driver_data;
unsigned int close_delay;
if (tty->index == MAX_PORTS) if (tty->index == MAX_PORTS)
return -EINVAL; return -EINVAL;
@ -2061,19 +2062,24 @@ static int moxa_set_serial_info(struct tty_struct *tty,
ss->baud_base != 921600) ss->baud_base != 921600)
return -EPERM; return -EPERM;
close_delay = msecs_to_jiffies(ss->close_delay * 10);
mutex_lock(&info->port.mutex); mutex_lock(&info->port.mutex);
if (!capable(CAP_SYS_ADMIN)) { 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))) { (info->port.flags & ~ASYNC_USR_MASK))) {
mutex_unlock(&info->port.mutex); mutex_unlock(&info->port.mutex);
return -EPERM; return -EPERM;
} }
} } else {
info->port.close_delay = msecs_to_jiffies(ss->close_delay * 10); 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); mutex_unlock(&info->port.mutex);
return 0; return 0;
} }