From mboxrd@z Thu Jan 1 00:00:00 1970 From: Herbert Xu Subject: [PATCH v2] crypto: x86/chacha20 - Manually align stack buffer Date: Wed, 11 Jan 2017 20:28:06 +0800 Message-ID: <20170111122806.GA9056@gondor.apana.org.au> References: <20170111120816.GA9004@gondor.apana.org.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Linux Crypto Mailing List To: Ard Biesheuvel Return-path: Received: from helcar.hengli.com.au ([209.40.204.226]:39191 "EHLO helcar.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750924AbdAKM2d (ORCPT ); Wed, 11 Jan 2017 07:28:33 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-crypto-owner@vger.kernel.org List-ID: On Wed, Jan 11, 2017 at 12:14:24PM +0000, Ard Biesheuvel wrote: > > I think the old code was fine, actually: > > u32 *state, state_buf[16 + (CHACHA20_STATE_ALIGN / sizeof(u32)) - 1]; > > ends up allocating 16 + 3 *words* == 64 + 12 bytes , which given the > guaranteed 4 byte alignment is sufficient for ensuring the pointer can > be 16 byte aligned. Ah yes you're right, it's a u32. > So [16 + 2] should be sufficient here Here's an updated version. ---8<--- The kernel on x86-64 cannot use gcc attribute align to align to a 16-byte boundary. This patch reverts to the old way of aligning it by hand. Fixes: 9ae433bc79f9 ("crypto: chacha20 - convert generic and...") Signed-off-by: Herbert Xu diff --git a/arch/x86/crypto/chacha20_glue.c b/arch/x86/crypto/chacha20_glue.c index 78f75b0..1e6af1b 100644 --- a/arch/x86/crypto/chacha20_glue.c +++ b/arch/x86/crypto/chacha20_glue.c @@ -67,10 +67,13 @@ static int chacha20_simd(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct chacha20_ctx *ctx = crypto_skcipher_ctx(tfm); - u32 state[16] __aligned(CHACHA20_STATE_ALIGN); + u32 *state, state_buf[16 + 2] __aligned(8); struct skcipher_walk walk; int err; + BUILD_BUG_ON(CHACHA20_STATE_ALIGN != 16); + state = PTR_ALIGN(state_buf + 0, CHACHA20_STATE_ALIGN); + if (req->cryptlen <= CHACHA20_BLOCK_SIZE || !may_use_simd()) return crypto_chacha20_crypt(req); -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt