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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+13cb3b01d0784e4ffc3f@syzkaller.appspotmail.com,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Peter Hutterer <peter.hutterer@who-t.net>,
        Dmitry Torokhov <dmitry.torokhov@gmail.com>
Subject: [PATCH 4.19 032/110] Input: synaptics - avoid using uninitialized variable when probing
Date:   Thu, 29 Nov 2018 15:12:03 +0100
Message-Id: <20181129135922.565401586@linuxfoundation.org>
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4.19-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dmitry Torokhov <dmitry.torokhov@gmail.com>

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>

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

--- a/drivers/input/mouse/synaptics.c
+++ b/drivers/input/mouse/synaptics.c
@@ -99,9 +99,7 @@ static int synaptics_mode_cmd(struct psm
 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);