media: ttusb-dec: Fix info-leak in ttusb_dec_send_command()

The function at issue does not always initialize each byte allocated
for 'b' and can therefore leak uninitialized memory to a USB device in
the call to usb_bulk_msg()

Use kzalloc() instead of kmalloc()

Signed-off-by: Tomas Bortoli <tomasbortoli@gmail.com>
Reported-by: syzbot+0522702e9d67142379f1@syzkaller.appspotmail.com
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/usb/ttusb-dec/ttusb_dec.c

@@ -319,7 +319,7 @@ static int ttusb_dec_send_command(struct ttusb_dec *dec, const u8 command,
 
 	dprintk("%s\n", __func__);
 
-	b = kmalloc(COMMAND_PACKET_SIZE + 4, GFP_KERNEL);
+	b = kzalloc(COMMAND_PACKET_SIZE + 4, GFP_KERNEL);
 	if (!b)
 		return -ENOMEM;