Input: synaptics - avoid using uninitialized variable when probing

commit f39f8688888ae74fa8deae2d01289b69b4727394 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: syzbot+13cb3b01d0784e4ffc3f@syzkaller.appspotmail.com
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index 6c4bbd38700e243b1eee15e8327532eb92af6e40..6f36e2d01e2e923979a5ef5e5c5ef03fc25693a1 100644 (file)
--- a/drivers/input/mouse/synaptics.c
+++ b/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);