Input: synaptics - avoid using uninitialized variable when probing

commit f39f868 upstream.

synaptics_detect() does not check whether sending commands to the
device succeeds and instead relies on getting unique data from the
device. Let's make sure we seed entire buffer with zeroes to make sure
we will not use garbage on stack that just happen to be 0x47.

Reported-by: [email protected]
Reviewed-by: Benjamin Tissoires <[email protected]>
Reviewed-by: Peter Hutterer <[email protected]>
Signed-off-by: Dmitry Torokhov <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

drivers/input/mouse/synaptics.c

@@ -99,9 +99,7 @@ static int synaptics_mode_cmd(struct psmouse *psmouse, u8 mode)
 int synaptics_detect(struct psmouse *psmouse, bool set_properties)
 {
 	struct ps2dev *ps2dev = &psmouse->ps2dev;
-	u8 param[4];
-
-	param[0] = 0;
+	u8 param[4] = { 0 };
 
 	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);
 	ps2_command(ps2dev, param, PSMOUSE_CMD_SETRES);