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 9F620C433ED for ; Mon, 19 Apr 2021 23:36:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 0DDBA6101C for ; Mon, 19 Apr 2021 23:36:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0DDBA6101C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 77A156B0036; Mon, 19 Apr 2021 19:36:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 729556B006E; Mon, 19 Apr 2021 19:36:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5A5226B0070; Mon, 19 Apr 2021 19:36:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0216.hostedemail.com [216.40.44.216]) by kanga.kvack.org (Postfix) with ESMTP id 3E7316B0036 for ; Mon, 19 Apr 2021 19:36:16 -0400 (EDT) Received: from smtpin03.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id E712E362B for ; Mon, 19 Apr 2021 23:36:15 +0000 (UTC) X-FDA: 78050727510.03.5EBFAC1 Received: from mail-pg1-f173.google.com (mail-pg1-f173.google.com [209.85.215.173]) by imf05.hostedemail.com (Postfix) with ESMTP id C6495E000105 for ; Mon, 19 Apr 2021 23:36:14 +0000 (UTC) Received: by mail-pg1-f173.google.com with SMTP id t22so25386508pgu.0 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=FmTss83fHBAACt/+ErkS0RJXH9ARi6uP8rFJ6sknkAOPTXwaLD5UcPbSuocTNfDM/7 me7xOI419/yd6YjdW3G/pTO/fUa2x1Q94KKlaNW3Zz1Kauh+cmMYM5xTOvcJdXRYRWOS flhDZrh94ARCUJ6or1XMiAf9513scVrKtOs1pGKbWWe4Ji6upnlCQEEa8HGWWBQJ0Bzi 1UL2LDGCI0ty4Wc5fWlbsAtrr7VbIV7fxeZu0Yv3iYfBqVI6Wxp3fHV06OZ217IO82Gk 3NHszyS1HiXV0CN4wsseHJxjtOaa2/Qy/Hrw4ufLSok+E8skLCzWTfYT6qalGeYlLpeo hJwQ== X-Gm-Message-State: AOAM5315hHPByhtl/kNHxDa8NlU54EPQLUPuOnCnqE+kVruHXqA2pcNw pSPVFbnL0rB11M/gWHjylLEA4A== 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: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: C6495E000105 X-Stat-Signature: yw7sy4b9juzrmh68qrepgb1oiz3jn6ay Received-SPF: none (chromium.org>: No applicable sender policy available) receiver=imf05; identity=mailfrom; envelope-from=""; helo=mail-pg1-f173.google.com; client-ip=209.85.215.173 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618875374-632792 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000007, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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