From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9ED20C10F27 for ; Tue, 10 Mar 2020 17:12:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 73E982146E for ; Tue, 10 Mar 2020 17:12:37 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="URGXY0PZ" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726445AbgCJRMh (ORCPT ); Tue, 10 Mar 2020 13:12:37 -0400 Received: from us-smtp-2.mimecast.com ([207.211.31.81]:53726 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726380AbgCJRMh (ORCPT ); Tue, 10 Mar 2020 13:12:37 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1583860355; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=OC/jw5IZXVx7wZDomW5T/X+1F9FrFuN9wQhaz4Xoo1Y=; b=URGXY0PZA2Kn7SbvBOJA6A26g5uvWyjxwC3lsrLgSOEsaT6LFgG68UVoW+LuBRdKW5xaGt cy0R2eiHemdNRGCXcTJdUVsrE3hC29+QvMXpOSfSWAs4dobptaGgM68+HMfz0+gUgppKim wnJIi6hIYC0PTeZmktOUvghCDSeTKTA= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-25-7QaVQKJVOA29IpYAOK_8NQ-1; Tue, 10 Mar 2020 13:12:34 -0400 X-MC-Unique: 7QaVQKJVOA29IpYAOK_8NQ-1 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 25C0B800D48; Tue, 10 Mar 2020 17:12:32 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-120-182.rdu2.redhat.com [10.10.120.182]) by smtp.corp.redhat.com (Postfix) with ESMTP id 3E11260BF3; Tue, 10 Mar 2020 17:12:24 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20200308170410.14166-3-longman@redhat.com> <20200308170410.14166-1-longman@redhat.com> <416690.1583771540@warthog.procyon.org.uk> To: Waiman Long Cc: dhowells@redhat.com, Jarkko Sakkinen , James Morris , "Serge E. Hallyn" , Mimi Zohar , keyrings@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org, Sumit Garg , Jerry Snitselaar , Roberto Sassu , Eric Biggers , Chris von Recklinghausen Subject: Re: [PATCH v2 2/2] KEYS: Avoid false positive ENOMEM error on key read MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <675399.1583860343.1@warthog.procyon.org.uk> Date: Tue, 10 Mar 2020 17:12:23 +0000 Message-ID: <675400.1583860343@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 Sender: linux-integrity-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-integrity@vger.kernel.org Waiman Long wrote: > That is not as simple as I thought. First of that, there is not an > equivalent kzvfree() helper to clear the buffer first before clearing. > Of course, I can do that manually. Yeah, the actual substance of vfree() may get deferred. It may be worth adding a kvzfree() that switches between kzfree() and memset(),vfree(). > With patch 2, the allocated buffer length will be max(1024, keylen). The > security code uses kmalloc() for allocation. If we use kvalloc() here, > perhaps we should also use that for allocation that can be potentially > large like that in big_key. What do you think? Not for big_key: if it's larger than BIG_KEY_FILE_THRESHOLD (~1KiB) it gets written encrypted into shmem so that it can be swapped out to disk when not in use. However, other cases, sure - just be aware that on a 32-bit system, vmalloc/vmap space is a strictly limited resource. David