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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 <johan@kernel.org>
Link: https://lore.kernel.org/r/20210407102334.32361-15-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Johan Hovold 2021-04-07 12:23:32 +02:00 committed by Greg Kroah-Hartman
parent be6cf583d2
commit b91cfb2573
1 changed files with 5 additions and 4 deletions
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9
drivers/tty/mxser.c
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@ -1270,6 +1270,7 @@ static int mxser_set_serial_info(struct tty_struct *tty,
if (!capable(CAP_SYS_ADMIN)) { if (!capable(CAP_SYS_ADMIN)) {
if ((ss->baud_base != info->baud_base) || if ((ss->baud_base != info->baud_base) ||
(close_delay != info->port.close_delay) || (close_delay != info->port.close_delay) ||
(closing_wait != info->port.closing_wait) ||
((ss->flags & ~ASYNC_USR_MASK) != (info->port.flags & ~ASYNC_USR_MASK))) { ((ss->flags & ~ASYNC_USR_MASK) != (info->port.flags & ~ASYNC_USR_MASK))) {
mutex_unlock(&port->mutex); mutex_unlock(&port->mutex);
return -EPERM; return -EPERM;
@ -1296,12 +1297,12 @@ static int mxser_set_serial_info(struct tty_struct *tty,
baud = ss->baud_base / ss->custom_divisor; baud = ss->baud_base / ss->custom_divisor;
tty_encode_baud_rate(tty, baud, baud); 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 (tty_port_initialized(port)) {
if (flags != (port->flags & ASYNC_SPD_MASK)) { if (flags != (port->flags & ASYNC_SPD_MASK)) {
spin_lock_irqsave(&info->slock, sl_flags); spin_lock_irqsave(&info->slock, sl_flags);