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=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 9614FC433ED for ; Mon, 19 Apr 2021 23:36:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 74A006135F for ; Mon, 19 Apr 2021 23:36:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232027AbhDSXgt (ORCPT ); Mon, 19 Apr 2021 19:36:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53842 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229842AbhDSXgp (ORCPT ); Mon, 19 Apr 2021 19:36:45 -0400 Received: from mail-pf1-x429.google.com (mail-pf1-x429.google.com [IPv6:2607:f8b0:4864:20::429]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 14B38C06174A for ; Mon, 19 Apr 2021 16:36:15 -0700 (PDT) Received: by mail-pf1-x429.google.com with SMTP id c3so5469881pfo.3 for ; Mon, 19 Apr 2021 16:36:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=+AXERFClYZYQUr1IqN7bGc0QBx+E2BeAvwA2SBiAo5U=; b=YmK13dmW5qtJCyvdmMQvQkEeNCJafx0yaLZuG+qt1h0kHyE16ZlbvlaKIXMdJuos0q oXaLUgrsIoOMW/QfJSmDcXcR6EX6TN/9FfVu/z3XvPw31FD3n4vWRmqF1KhC3Fyl4bE9 eEG4MsQbmbgtdohUERLAUr/uXceQgL/DsllmU= 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; bh=+AXERFClYZYQUr1IqN7bGc0QBx+E2BeAvwA2SBiAo5U=; b=RGMihg0aNeolYL+Dc4Kyy4HhPp+321SsNSWgwKNICYrncV6QtsOV3ax2Gn+BgCT8pT qEMAR88a2Vwr5EG0GsuC1t2EGdw/Grj/DsYXlR0m+ttX07/6FoLcSVNyuaP7O9bAp3KP p+sfcEhRYe5bkQ6Rz0OaY9j5DCQrODGLTQj52onP+4HM3mJzzgcz2vfN1bFeEEeyVaPj rrsy9iD20zjXfDreoXhCzx1FzyW+0KC3kCKrZ6kXeCgYrqEg11iLUQyZNbuBa77gP3ac hRMqhBQHR9rKUYCISCGI4y8yp8x1d1qquB1OLnKl50W6UBw/wHgNU01wmpLtRUAGv1wa Kp2Q== X-Gm-Message-State: AOAM530uMS+BbklmMirkU4UCXpD77A4xBoS9J/fZL3fcgpABHWyUTvuc zuRZIxLC81S5vHHzgUjHuFHowauV48NbUg== X-Google-Smtp-Source: ABdhPJzERC0jwguaNsJ+wSeg55qiPue3mqoTqTb9eYfqXtUH3uNdF0tKTOJIlM21AuWzWAGco92F6A== X-Received: by 2002:a62:ce42:0:b029:261:ab24:f65f with SMTP id y63-20020a62ce420000b0290261ab24f65fmr4572278pfg.18.1618875374515; Mon, 19 Apr 2021 16:36:14 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id o9sm14586976pfh.217.2021.04.19.16.36.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 19 Apr 2021 16:36:13 -0700 (PDT) Date: Mon, 19 Apr 2021 16:36:12 -0700 From: Kees Cook To: Peter Zijlstra Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, x86@kernel.org, jani.nikula@linux.intel.com, joonas.lahtinen@linux.intel.com, rodrigo.vivi@intel.com, chris@chris-wilson.co.uk, intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, hch@lst.de Subject: Re: [PATCH 4/7] mm: Introduce verify_page_range() Message-ID: <202104191630.F00A6AAF@keescook> References: <20210412080012.357146277@infradead.org> <20210412080611.769864829@infradead.org> <202104121302.57D7EF8@keescook> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 13, 2021 at 08:54:06AM +0200, Peter Zijlstra wrote: > On Mon, Apr 12, 2021 at 01:05:09PM -0700, Kees Cook wrote: > > On Mon, Apr 12, 2021 at 10:00:16AM +0200, Peter Zijlstra wrote: > > > +struct vpr_data { > > > + int (*fn)(pte_t pte, unsigned long addr, void *data); > > > + void *data; > > > +}; > > > > Eeerg. This is likely to become an attack target itself. Stored function > > pointer with stored (3rd) argument. > > You got some further reading on that? How exactly are those exploited? Sure, see "Executing code" in https://googleprojectzero.blogspot.com/2017/05/exploiting-linux-kernel-via-packet.html I killed the entire primitive (for timer_list) https://outflux.net/blog/archives/2018/02/05/security-things-in-linux-v4-15/#v4.15-timer_list but that was a lot of work, so I'm trying to avoid seeing more things like it appear. :) (And I'm trying to get rid of similar APIs, like tasklet.) This new code is unlikely to ever be used as widely as timer_list, but I just cringe when I see the code pattern. I'll understand if there isn't a solution that doesn't require major refactoring, but I can dream. :) -- Kees Cook