Staging: quickstart: Cleanup quickstart_acpi_ghid

Also fix memory leak (buffer.pointer) when returned buffer of length
less than 8.

Signed-off-by: Szymon Janc <szymon@janc.net.pl>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/staging/quickstart/quickstart.c b/drivers/staging/quickstart/quickstart.c
index 7b0deb65cf409eae4edba4167e81d464c5fe8814..3bae5e7565983072670097398680d32c9a8b83ab 100644 (file)
--- a/drivers/staging/quickstart/quickstart.c
+++ b/drivers/staging/quickstart/quickstart.c
@@ -191,14 +191,11 @@ static void quickstart_acpi_notify(acpi_handle handle, u32 event, void *data)
        return;
 }
 
-static void quickstart_acpi_ghid(struct quickstart_acpi *quickstart)
+static int quickstart_acpi_ghid(struct quickstart_acpi *quickstart)
 {
        acpi_status status;
        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
-       uint32_t usageid = 0;
-
-       if (!quickstart)
-               return;
+       int ret = 0;
 
        /*
         * This returns a buffer telling the button usage ID,
@@ -206,24 +203,41 @@ static void quickstart_acpi_ghid(struct quickstart_acpi *quickstart)
         */
        status = acpi_evaluate_object(quickstart->device->handle, "GHID", NULL,
                                                                &buffer);
-       if (ACPI_FAILURE(status) || !buffer.pointer) {
+       if (ACPI_FAILURE(status)) {
                printk(KERN_ERR "quickstart: %s GHID method failed.\n",
                                                quickstart->btn->name);
-               return;
+               return -EINVAL;
        }
 
-       if (buffer.length < 8)
-               return;
-
        /*
         * <<The GHID method can return a BYTE, WORD, or DWORD.
         * The value must be encoded in little-endian byte
         * order (least significant byte first).>>
         */
-       usageid = *((uint32_t *)(buffer.pointer + (buffer.length - 8)));
-       quickstart->btn->id = usageid;
+       switch (buffer.length) {
+       case 1:
+               quickstart->btn->id = *(uint8_t *)buffer.pointer;
+               break;
+       case 2:
+               quickstart->btn->id = *(uint16_t *)buffer.pointer;
+               break;
+       case 4:
+               quickstart->btn->id = *(uint32_t *)buffer.pointer;
+               break;
+       case 8:
+               quickstart->btn->id = *(uint64_t *)buffer.pointer;
+               break;
+       default:
+               printk(KERN_ERR "quickstart: %s GHID method returned buffer "
+                               "of unexpected length %u\n",
+                               quickstart->btn->name, buffer.length);
+               ret = -EINVAL;
+               break;
+       }
 
        kfree(buffer.pointer);
+
+       return ret;
 }
 
 static int quickstart_acpi_config(struct quickstart_acpi *quickstart, char *bid)