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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL autolearn=ham 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 EB694C433E0 for ; Thu, 18 Mar 2021 18:44:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B608A64F01 for ; Thu, 18 Mar 2021 18:44:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232647AbhCRSoP (ORCPT ); Thu, 18 Mar 2021 14:44:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53828 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232710AbhCRSno (ORCPT ); Thu, 18 Mar 2021 14:43:44 -0400 Received: from mail-lf1-x12c.google.com (mail-lf1-x12c.google.com [IPv6:2a00:1450:4864:20::12c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8D92DC061761 for ; Thu, 18 Mar 2021 11:43:43 -0700 (PDT) Received: by mail-lf1-x12c.google.com with SMTP id x28so6171246lfu.6 for ; Thu, 18 Mar 2021 11:43:43 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=nO1NtgEydXG2HLjdhqcJj5jPeQtrUPiYrY1ZDV7Qq/s=; b=iVhfN+7riOgr03gvFp6rabJN8XblDjHGtyOGptCHZxdhiECWH17xolvbVqxD61vi5I j7wFaX5OK16XDA5OTljEBtUkLE2p3wAIHOYdcH8ygbsif54rpWGXfnIWvKORxYc4UJ1w 6dpCNm4hA+O3GYVYuNboKJbPCS8Oh2iWIqDuNjVnnqHZcMpWEB+u61udXs5p4zIplHiH CBdgrX3qELlJwkMMudYSduN4JtzCQ0guTsDLtI6hfWhmcv5TSoKkA2uF2dne+wk64bzA vhgHY9WcBAhuoxiLklXUyWlxBSx7Duidr12ctcSGZeFqB3A/j6mB7xOZA+MdIuSjYEd1 X7hw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=nO1NtgEydXG2HLjdhqcJj5jPeQtrUPiYrY1ZDV7Qq/s=; b=h3EO0TdwZ25mcBqu7Mo0cGZIKNyyHlLuwz3vvSmcTI9Aba/yUN70pTYC/gntzKNl5H 0QqSHcQaS1kDl7+kwYWhhgvujlQuQ8rOL/ol0/B4PgHg0pNVTO79yHwG6Z9guY0J/UHk +BQDZQ8LihERnY5vhjJ5MMV7S5OfhWtGK1Q2mSO1SfKTu/+WWBW+uLV3k+Z4piSNou6y J9G/N4xbsYsRHIGmWZ/v+zEKeg1kM7ZI+awPQPtO8M2C4d7BNiXwMK8oy4MxDKmXIsr2 TuNCWH6rOInRF50PKNod8R7pI2Aw1dWvSnn2gZP+7W6Vm2u2ywDSwdeRlkYoDTlm2WmE 4bLA== X-Gm-Message-State: AOAM531zsPrWykR8MKLFfymdKq3gY98EljQOhmr9lvzswlQJXnyOVe2U 0mTVZVut60NvWJLvDk0do/j9WB4c45DHfq1M5SVbDg== X-Google-Smtp-Source: ABdhPJwPMFefAwqyWlFWcoKbDZciOiKnXiRQmrMNGrG6rw2lNtQsSLGJF3SwnZ8fBikFCSYXYvEuLtpI1LrMEMs5+eI= X-Received: by 2002:ac2:532c:: with SMTP id f12mr6587813lfh.73.1616093021734; Thu, 18 Mar 2021 11:43:41 -0700 (PDT) MIME-Version: 1.0 References: <20210318171111.706303-1-samitolvanen@google.com> <20210318171111.706303-11-samitolvanen@google.com> In-Reply-To: <20210318171111.706303-11-samitolvanen@google.com> From: Nick Desaulniers Date: Thu, 18 Mar 2021 11:43:29 -0700 Message-ID: Subject: Re: [PATCH v2 10/17] lkdtm: use __va_function To: Sami Tolvanen Cc: Kees Cook , Nathan Chancellor , Masahiro Yamada , Will Deacon , Jessica Yu , Arnd Bergmann , Tejun Heo , "Paul E. McKenney" , Christoph Hellwig , bpf , linux-hardening@vger.kernel.org, linux-arch , Linux ARM , Linux Kbuild mailing list , PCI , LKML Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Thu, Mar 18, 2021 at 10:11 AM Sami Tolvanen wrote: > > To ensure we take the actual address of a function in kernel text, use > __va_function. Otherwise, with CONFIG_CFI_CLANG, the compiler replaces > the address with a pointer to the CFI jump table, which is actually in > the module when compiled with CONFIG_LKDTM=m. Should patch 10 and 12 be reordered against one another? Otherwise it looks like 12 defines __va_function while 10 uses it? > > Signed-off-by: Sami Tolvanen > Acked-by: Kees Cook > --- > drivers/misc/lkdtm/usercopy.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/misc/lkdtm/usercopy.c b/drivers/misc/lkdtm/usercopy.c > index 109e8d4302c1..d173d6175c87 100644 > --- a/drivers/misc/lkdtm/usercopy.c > +++ b/drivers/misc/lkdtm/usercopy.c > @@ -314,7 +314,7 @@ void lkdtm_USERCOPY_KERNEL(void) > > pr_info("attempting bad copy_to_user from kernel text: %px\n", > vm_mmap); > - if (copy_to_user((void __user *)user_addr, vm_mmap, > + if (copy_to_user((void __user *)user_addr, __va_function(vm_mmap), > unconst + PAGE_SIZE)) { > pr_warn("copy_to_user failed, but lacked Oops\n"); > goto free_user; > -- > 2.31.0.291.g576ba9dcdaf-goog > -- Thanks, ~Nick Desaulniers