Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935091AbcLMRI6 (ORCPT ); Tue, 13 Dec 2016 12:08:58 -0500 Received: from mail-vk0-f52.google.com ([209.85.213.52]:36357 "EHLO mail-vk0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932914AbcLMRHn (ORCPT ); Tue, 13 Dec 2016 12:07:43 -0500 MIME-Version: 1.0 In-Reply-To: <20161213033928.GB5601@gondor.apana.org.au> References: <20161209230851.GB64048@google.com> <20161213033928.GB5601@gondor.apana.org.au> From: Andy Lutomirski Date: Tue, 13 Dec 2016 09:06:31 -0800 Message-ID: Subject: Re: Remaining crypto API regressions with CONFIG_VMAP_STACK To: Herbert Xu Cc: Eric Biggers , linux-crypto@vger.kernel.org, "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" , "kernel-hardening@lists.openwall.com" , Andrew Lutomirski , Stephan Mueller Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1326 Lines: 37 On Mon, Dec 12, 2016 at 7:39 PM, Herbert Xu wrote: > On Mon, Dec 12, 2016 at 10:34:10AM -0800, Andy Lutomirski wrote: >> >> Here's my status. >> >> > drivers/crypto/bfin_crc.c:351 >> > drivers/crypto/qce/sha.c:299 >> > drivers/crypto/sahara.c:973,988 >> > drivers/crypto/talitos.c:1910 >> > drivers/crypto/qce/sha.c:325 >> >> I have a patch to make these depend on !VMAP_STACK. > > Why? They're all marked as ASYNC AFAIK. > >> I have a patch to convert this to, drumroll please: >> >> priv->tx_tfm_mic = crypto_alloc_shash("michael_mic", 0, >> CRYPTO_ALG_ASYNC); >> >> Herbert, I'm at a loss as what a "shash" that's "ASYNC" even means. > > Having 0 as type and CRYPTO_ALG_ASYNC as mask in general means > that we're requesting a sync algorithm (i.e., ASYNC bit off). > > However, it is completely unnecessary for shash as they can never > be async. So this could be changed to just ("michael_mic", 0, 0). I'm confused by a bunch of this. 1. Is it really the case that crypto_alloc_xyz(..., CRYPTO_ALG_ASYNC) means to allocate a *synchronous* transform? That's not what I expected. 2. What guarantees that an async request is never allocated on the stack? If it's just convention, could an assertion be added somewhere?