diff options
| author | Peter Hurley <peter@hurleysoftware.com> | 2016-01-13 02:14:46 +0300 |
|---|---|---|
| committer | Luis Henriques <luis.henriques@canonical.com> | 2016-02-25 13:34:47 +0300 |
| commit | 546e99d81f7b365d25ae61318d9113a26bef806f (patch) | |
| tree | 04285da387f582bf52d27051192fa05e8ac53966 /drivers | |
| parent | 113241155f8133906a549cffafc60957fddaaa5f (diff) | |
| download | linux-546e99d81f7b365d25ae61318d9113a26bef806f.tar.xz | |
serial: omap: Prevent DoS using unprivileged ioctl(TIOCSRS485)
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>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/tty/serial/omap-serial.c | 8 |
1 files changed, 6 insertions, 2 deletions
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c index e454b7c2ecd9..9053aa7a970f 100644 --- a/drivers/tty/serial/omap-serial.c +++ b/drivers/tty/serial/omap-serial.c @@ -1350,7 +1350,7 @@ static inline void serial_omap_add_console_port(struct uart_omap_port *up) /* Enable or disable the rs485 support */ static void -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 long flags; @@ -1365,8 +1365,12 @@ 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 */ - up->rs485 = *rs485conf; + up->rs485 = *rs485; /* * Just as a precaution, only allow rs485 |