diff --git a/drivers/acpi/custom_method.c b/drivers/acpi/custom_method.c
index 7b54dc95d36b..fa9f7ff4a3a6 100644
--- a/drivers/acpi/custom_method.c
+++ b/drivers/acpi/custom_method.c
@@ -55,6 +55,7 @@ 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;
 	}
 
@@ -76,7 +77,6 @@ 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;
 }