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authorPeter Hurley <peter@hurleysoftware.com>2016-01-12 15:14:46 -0800
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-02-06 23:04:51 -0800
commit308bbc9ab838d0ace0298268c7970ba9513e2c65 (patch)
treed9f36e4b088a95cfffd280cda838ff4a3f5cbcc9 /drivers/tty
parentd56edd7ed0ed46a8043ee3040ededbd190818ccf (diff)
downloadlinux-308bbc9ab838d0ace0298268c7970ba9513e2c65.tar.bz2
serial: omap: Prevent DoS using unprivileged ioctl(TIOCSRS485)
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") Cc: <stable@vger.kernel.org> # 3.12+ Signed-off-by: Peter Hurley <peter@hurleysoftware.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r--drivers/tty/serial/omap-serial.c8
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index b645f9228ed7..27d3b978f16e 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1343,7 +1343,7 @@ 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;
@@ -1356,8 +1356,12 @@ 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