diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index 1ed6d24ae1c945753c2a267efc6f5f3af475b7ef..613041870872b87f024da944df74a992e5d90c62 100644
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -52,6 +52,7 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,
 	    (*ppos + count < count) ||
 	    (count > uncopied_bytes)) {
 		kfree(buf);
+		buf = NULL;
 		return -EINVAL;
 	}
 
@@ -73,7 +74,6 @@ static ssize_t cm_write(struct file *file, const char __user * user_buf,
 		add_taint(TAINT_OVERRIDDEN_ACPI_TABLE, LOCKDEP_NOW_UNRELIABLE);
 	}
 
-	kfree(buf);
 	return count;
 }