[PATCH] HID: lenovo: Don't use stack variables for DMA buffers

[Josh Boyer]

The lenovo_send_cmd_cptkbd function uses a stack variable to submit
commands via hid_hw_raw_request.  Eventually this gets to the
usb_hcd_map_urb_for_dma function, which causes a warning to be thrown
if the CONFIG_DMA_API_DEBUG option is enabled.

Fix this by allocating a temporary buffer instead.

Reported-by: lejeczek <pelj...@yahoo.co.uk>
Signed-off-by: Josh Boyer <jwbo...@fedoraproject.org>
---
 drivers/hid/hid-lenovo.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/hid/hid-lenovo.c b/drivers/hid/hid-lenovo.c
index 0125e356bd8d..2ba5e8ea66a4 100644
--- a/drivers/hid/hid-lenovo.c
+++ b/drivers/hid/hid-lenovo.c
@@ -184,21 +184,31 @@ static int lenovo_send_cmd_cptkbd(struct hid_device *hdev,
                        unsigned char byte2, unsigned char byte3)
 {
        int ret;
-       unsigned char buf[] = {0x18, byte2, byte3};
+       unsigned char *buf = NULL;
+
+       buf = kzalloc(3, GFP_KERNEL);
+       if (!buf)
+               return -ENOMEM;
+
+       buf[0] = 0x18;
+       buf[1] = byte2;
+       buf[2] = byte3;
 
        switch (hdev->product) {
        case USB_DEVICE_ID_LENOVO_CUSBKBD:
-               ret = hid_hw_raw_request(hdev, 0x13, buf, sizeof(buf),
+               ret = hid_hw_raw_request(hdev, 0x13, buf, 3,
                                        HID_FEATURE_REPORT, HID_REQ_SET_REPORT);
                break;
        case USB_DEVICE_ID_LENOVO_CBTKBD:
-               ret = hid_hw_output_report(hdev, buf, sizeof(buf));
+               ret = hid_hw_output_report(hdev, buf, 3);
                break;
        default:
                ret = -EINVAL;
                break;
        }
 
+       kfree(buf);
+
        return ret < 0 ? ret : 0; /* BT returns 0, USB returns sizeof(buf) */
 }
 
-- 
2.5.5