From f39f8688888ae74fa8deae2d01289b69b4727394 Mon Sep 17 00:00:00 2001
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: Tue, 16 Oct 2018 17:07:35 -0700
Subject: [PATCH] Input: synaptics - avoid using uninitialized variable when probing
Git-commit: f39f8688888ae74fa8deae2d01289b69b4727394
Patch-mainline: v4.20-rc1
References: bsc#1051510

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/input/mouse/synaptics.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/drivers/input/mouse/synaptics.c b/drivers/input/mouse/synaptics.c
index 55d33500d55e..5e85f3cca867 100644
--- 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);
-- 
2.19.1