Bluetooth: btmtk: Fix short read errors in btmtk_usb_reg_read()

If btmtk_usb_reg_read() gets a "short" read from a device, it will
accidentally treat that as a "real" read and populate the returned value
with some unknown and probably totally invalid data.

Fix this logic error up by calling usb_control_msg_recv() which
guarantees a "full" read happens, and then simplify the error checking
for when btmtk_usb_reg_read() is called (it's really just
btmtk_usb_id_get() that calls btmtk_usb_reg_read(), so fix up those
return sites.

Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/drivers/bluetooth/btmtk.c b/drivers/bluetooth/btmtk.c
index 6f060e4433db188fb23a86262aff39c5e2f3edaf..66b34676104362435cffaa9b433e31474a74f9b6 100644 (file)
--- a/drivers/bluetooth/btmtk.c
+++ b/drivers/bluetooth/btmtk.c
@@ -827,27 +827,21 @@ static int btmtk_usb_uhw_reg_read(struct hci_dev *hdev, u32 reg, u32 *val)
 static int btmtk_usb_reg_read(struct hci_dev *hdev, u32 reg, u32 *val)
 {
        struct btmtk_data *data = hci_get_priv(hdev);
-       int pipe, err, size = sizeof(u32);
-       void *buf;
-
-       buf = kzalloc(size, GFP_KERNEL);
-       if (!buf)
-               return -ENOMEM;
+       u8 buf[sizeof(u32)];
+       int err;
 
-       pipe = usb_rcvctrlpipe(data->udev, 0);
-       err = usb_control_msg(data->udev, pipe, 0x63,
-                             USB_TYPE_VENDOR | USB_DIR_IN,
-                             reg >> 16, reg & 0xffff,
-                             buf, size, USB_CTRL_GET_TIMEOUT);
+       *val = 0;
+       err = usb_control_msg_recv(data->udev, 0, 0x63,
+                                  USB_TYPE_VENDOR | USB_DIR_IN,
+                                  reg >> 16, reg & 0xffff,
+                                  buf, sizeof(buf), USB_CTRL_GET_TIMEOUT,
+                                  GFP_KERNEL);
        if (err < 0)
-               goto err_free_buf;
+               return err;
 
        *val = get_unaligned_le32(buf);
 
-err_free_buf:
-       kfree(buf);
-
-       return err;
+       return 0;
 }
 
 static int btmtk_usb_id_get(struct hci_dev *hdev, u32 reg, u32 *id)
@@ -974,7 +968,7 @@ int btmtk_usb_subsys_reset(struct hci_dev *hdev, u32 dev_id)
        }
 
        err = btmtk_usb_id_get(hdev, 0x70010200, &val);
-       if (err < 0 || (!val && dev_id != 0x6639))
+       if (err || (!val && dev_id != 0x6639))
                bt_dev_err(hdev, "Can't get device id, subsys reset fail.");
 
        return err;
@@ -1318,24 +1312,24 @@ int btmtk_usb_setup(struct hci_dev *hdev)
        calltime = ktime_get();
 
        err = btmtk_usb_id_get(hdev, 0x80000008, &dev_id);
-       if (err < 0) {
+       if (err) {
                bt_dev_err(hdev, "Failed to get device id (%d)", err);
                return err;
        }
 
        if (!dev_id || dev_id != 0x7663) {
                err = btmtk_usb_id_get(hdev, 0x70010200, &dev_id);
-               if (err < 0) {
+               if (err) {
                        bt_dev_err(hdev, "Failed to get device id (%d)", err);
                        return err;
                }
                err = btmtk_usb_id_get(hdev, 0x80021004, &fw_version);
-               if (err < 0) {
+               if (err) {
                        bt_dev_err(hdev, "Failed to get fw version (%d)", err);
                        return err;
                }
                err = btmtk_usb_id_get(hdev, 0x70010020, &fw_flavor);
-               if (err < 0) {
+               if (err) {
                        bt_dev_err(hdev, "Failed to get fw flavor (%d)", err);
                        return err;
                }