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=1.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,FSL_HELO_FAKE, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 CDE6EC43141 for ; Wed, 20 Jun 2018 23:46:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7979820874 for ; Wed, 20 Jun 2018 23:46:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="IBOfMP60" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7979820874 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933179AbeFTXq2 (ORCPT ); Wed, 20 Jun 2018 19:46:28 -0400 Received: from mail-pg0-f65.google.com ([74.125.83.65]:41935 "EHLO mail-pg0-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932571AbeFTXq0 (ORCPT ); Wed, 20 Jun 2018 19:46:26 -0400 Received: by mail-pg0-f65.google.com with SMTP id l65-v6so517359pgl.8; Wed, 20 Jun 2018 16:46:26 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=zV6LWz+iWOUTtp4Rbm+IZ6FXkTvO+aq6ljNKIufeUFU=; b=IBOfMP60t5q2WIymX01V+ts9xOHTT5fPUijOWDk866qRAj/FKfi09SFqhfO41yFDFc dO6P9o4pKYvwZGL7b2gAJHGxWY7RWxWhvM7ZRF2e4jUV9vg6KHZByl4Lb9nr7i8FZhiI xEDpgUOodutzTKncrjz1wIXm2Lf3G8l92nMD+WvBKEcu5nc57X0mJBjXnv7Wa9xXGZ3H 4ND7sT+4iS+Qkc9Mt8p72NjdjMDCaXvs5PxdSav4bYTPNqT2KjbMuqgdAtqQmDpRWUCl C4Amj6/2s5BKmgX9Nlp3FUrQvkdnSYOPcDVCvPXl3Awm00jl9enga3qnH4G3ydYW7UA4 thVg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=zV6LWz+iWOUTtp4Rbm+IZ6FXkTvO+aq6ljNKIufeUFU=; b=eYd1ViNLAMBBekcM79p8G0s4RM9yyFI5abdCRcCGBZk11RNg06V90HJFeiixzIlH0d 35V+BrzH1jAFgB/qAhRFanJhz3UeOnpfIwqGgMSRDm3oHb1bfcf0CHpcSiXrx+iDSUWW YDLtuBuELbwdmnFXmYkYtBbkVgnU1LMN60D4xUusao8ohP6zerB7n1KMiwmJbu3VA2wp 2twNc1+xctepWnBjPliesuDR/F34AcVTlnFLHF7Sh4D9oBgByjRDatr0DgJlDzJnRquV bdUJSKpn5BKc4b3f9SdNxbxF4oXPNOaKW+a/p/ZrjEPgdwmNDlNxbbWm8nJ0a0mZ79Mp jy4A== X-Gm-Message-State: APt69E0vmqTmQAVU6fjEiztZLogM6aMOopb5oEXZshds0g5biqs22X1f NlhPVCULdgYgHSY5W3uvq7g= X-Google-Smtp-Source: ADUXVKLd8t1blXLRzhrhFwDThieMG1kQuu024OHtWKNpBSRriMr0iqe4HNk0UrhjSYx4l2c1wx1Ozg== X-Received: by 2002:a65:51c9:: with SMTP id i9-v6mr20737116pgq.202.1529538385815; Wed, 20 Jun 2018 16:46:25 -0700 (PDT) Received: from gmail.com ([2620:15c:17:3:dc28:5c82:b905:e8a8]) by smtp.gmail.com with ESMTPSA id x72-v6sm7168313pff.176.2018.06.20.16.46.25 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 20 Jun 2018 16:46:25 -0700 (PDT) Date: Wed, 20 Jun 2018 16:46:23 -0700 From: Eric Biggers To: Kees Cook Cc: Herbert Xu , Giovanni Cabiddu , Arnd Bergmann , Eric Biggers , Mike Snitzer , "Gustavo A. R. Silva" , qat-linux@intel.com, linux-kernel@vger.kernel.org, dm-devel@redhat.com, linux-crypto@vger.kernel.org, Lars Persson , Tim Chen , "David S. Miller" , Alasdair Kergon , Rabin Vincent Subject: Re: [dm-devel] [PATCH 07/11] crypto: xcbc: Remove VLA usage Message-ID: <20180620234623.GE111712@gmail.com> References: <20180620190408.45104-1-keescook@chromium.org> <20180620190408.45104-8-keescook@chromium.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180620190408.45104-8-keescook@chromium.org> User-Agent: Mutt/1.10+28 (db52f11e) (2018-06-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 20, 2018 at 12:04:04PM -0700, Kees Cook wrote: > In the quest to remove all stack VLA usage from the kernel[1], this uses > the maximum blocksize and adds a sanity check. > > [1] https://lkml.kernel.org/r/CA+55aFzCG-zNmZwX4A2FQpadafLfEzK6CC=qPXydAacU1RqZWA@mail.gmail.com > > Signed-off-by: Kees Cook > --- > crypto/xcbc.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/crypto/xcbc.c b/crypto/xcbc.c > index 25c75af50d3f..016481b1f3ba 100644 > --- a/crypto/xcbc.c > +++ b/crypto/xcbc.c > @@ -65,7 +65,10 @@ static int crypto_xcbc_digest_setkey(struct crypto_shash *parent, > int bs = crypto_shash_blocksize(parent); > u8 *consts = PTR_ALIGN(&ctx->ctx[0], alignmask + 1); > int err = 0; > - u8 key1[bs]; > + u8 key1[CRYPTO_ALG_MAX_BLOCKSIZE]; > + > + if (WARN_ON(bs > sizeof(key1))) > + return -EINVAL; Similarly, why not MAX_CIPHER_BLOCKSIZE? Also, xcbc_create() only allows a 16-byte block size, and you made the API enforce the maximum for algorithms anyway. So I think the extra check here isn't very worthwhile. - Eric