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serial: return -EINVAL for non-legacy RS485 flags

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In order to be add new flags more cleanly and safely, return -EINVAL
from TIOCSRS485 ioctl for the flags bits which are not among the
current legacy ones.

This might cause a regression for userspace as those non-flag bits do
not currently trigger -EINVAL. However, it would only occur if the
userspace is sending garbage bits so perhaps we'll get away with this
change.

Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220606100433.13793-25-ilpo.jarvinen@linux.intel.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ilpo Järvinen 2022-06-06 13:04:21 +03:00 committed by Greg Kroah-Hartman
parent 596a917147
commit 51ad36baac
1 changed files with 24 additions and 0 deletions
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24
drivers/tty/serial/serial_core.c
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@ -1276,6 +1276,27 @@ static int uart_get_icount(struct tty_struct *tty,
return 0;
}
#define SER_RS485_LEGACY_FLAGS (SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | \
SER_RS485_RTS_AFTER_SEND | SER_RS485_RX_DURING_TX | \
SER_RS485_TERMINATE_BUS)
static int uart_check_rs485_flags(struct uart_port *port, struct serial_rs485 *rs485)
{
u32 flags = rs485->flags;
/* Don't return -EINVAL for unsupported legacy flags */
flags &= ~SER_RS485_LEGACY_FLAGS;
/*
* For any bit outside of the legacy ones that is not supported by
* the driver, return -EINVAL.
*/
if (flags & ~port->rs485_supported->flags)
return -EINVAL;
return 0;
}
static void uart_sanitize_serial_rs485(struct uart_port *port, struct serial_rs485 *rs485)
{
u32 supported_flags = port->rs485_supported->flags;
@ -1375,6 +1396,9 @@ static int uart_set_rs485_config(struct uart_port *port,
if (copy_from_user(&rs485, rs485_user, sizeof(*rs485_user)))
return -EFAULT;
ret = uart_check_rs485_flags(port, &rs485);
if (ret)
return ret;
uart_sanitize_serial_rs485(port, &rs485);
spin_lock_irqsave(&port->lock, flags);