lkml.org 
[lkml]   [2016]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.2.y-ckt 117/273] serial: omap: Prevent DoS using unprivileged ioctl(TIOCSRS485)
    Date
    4.2.8-ckt5 -stable review patch.  If anyone has any objections, please let me know.

    ---8<------------------------------------------------------------

    From: Peter Hurley <peter@hurleysoftware.com>

    commit 308bbc9ab838d0ace0298268c7970ba9513e2c65 upstream.

    The omap-serial driver emulates RS485 delays using software timers,
    but neglects to clamp the input values from the unprivileged
    ioctl(TIOCSRS485). Because the software implementation busy-waits,
    malicious userspace could stall the cpu for ~49 days.

    Clamp the input values to < 100ms.

    Fixes: 4a0ac0f55b18 ("OMAP: add RS485 support")
    Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Kamal Mostafa <kamal@canonical.com>
    ---
    drivers/tty/serial/omap-serial.c | 8 ++++++--
    1 file changed, 6 insertions(+), 2 deletions(-)

    diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
    index 7a2172b..aaf3478 100644
    --- a/drivers/tty/serial/omap-serial.c
    +++ b/drivers/tty/serial/omap-serial.c
    @@ -1341,7 +1341,7 @@ static inline void serial_omap_add_console_port(struct uart_omap_port *up)

    /* Enable or disable the rs485 support */
    static int
    -serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
    +serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
    {
    struct uart_omap_port *up = to_uart_omap_port(port);
    unsigned int mode;
    @@ -1354,8 +1354,12 @@ serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
    up->ier = 0;
    serial_out(up, UART_IER, 0);

    + /* Clamp the delays to [0, 100ms] */
    + rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
    + rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U);
    +
    /* store new config */
    - port->rs485 = *rs485conf;
    + port->rs485 = *rs485;

    /*
    * Just as a precaution, only allow rs485
    --
    2.7.0
    \
     
     \ /
      Last update: 2016-03-08 01:41    [W:4.041 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site