Staging: asus_oled: Add NULL test for kmalloc

This patch adds a NULL test to check wether kmalloc was successful or
not.
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/asus_oled/asus_oled.c

@@ -430,6 +430,11 @@ static ssize_t odev_set_picture(struct asus_oled_dev *odev,
 
 		kfree(odev->buf);
 		odev->buf = kmalloc(odev->buf_size, GFP_KERNEL);
+		if (odev->buf == NULL) {
+			odev->buf_size = 0;
+			printk(ASUS_OLED_ERROR "Out of memory!\n");
+			return -ENOMEM;
+		}
 
 		memset(odev->buf, 0xff, odev->buf_size);