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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 B8E3BCA9EC5 for ; Wed, 30 Oct 2019 19:26:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9379420717 for ; Wed, 30 Oct 2019 19:26:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726841AbfJ3T0g (ORCPT ); Wed, 30 Oct 2019 15:26:36 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:35269 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726769AbfJ3T0g (ORCPT ); Wed, 30 Oct 2019 15:26:36 -0400 Received: from in01.mta.xmission.com ([166.70.13.51]) by out02.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1iPtby-000758-Jv; Wed, 30 Oct 2019 13:26:30 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1iPtbx-0007ls-C9; Wed, 30 Oct 2019 13:26:30 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Andrea Righi Cc: Dan Carpenter , Bartlomiej Zolnierkiewicz , Daniel Vetter , Sam Ravnborg , Maarten Lankhorst , Peter Rosin , Gerd Hoffmann , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, security@kernel.org, Kees Cook , Julia Lawall References: <20191029182320.GA17569@mwanda> <87zhhjjryk.fsf@x220.int.ebiederm.org> <20191030074321.GD2656@xps-13> Date: Wed, 30 Oct 2019 14:26:21 -0500 In-Reply-To: <20191030074321.GD2656@xps-13> (Andrea Righi's message of "Wed, 30 Oct 2019 08:43:21 +0100") Message-ID: <87r22ujaqq.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1iPtbx-0007ls-C9;;;mid=<87r22ujaqq.fsf@x220.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX19FbjDNGFR7y0rdUnCUnTTvGuw2gDijzYQ= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH] fbdev: potential information leak in do_fb_ioctl() X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrea Righi writes: > On Tue, Oct 29, 2019 at 02:02:11PM -0500, Eric W. Biederman wrote: >> Dan Carpenter writes: >> >> > The "fix" struct has a 2 byte hole after ->ywrapstep and the >> > "fix = info->fix;" assignment doesn't necessarily clear it. It depends >> > on the compiler. >> > >> > Fixes: 1f5e31d7e55a ("fbmem: don't call copy_from/to_user() with mutex held") >> > Signed-off-by: Dan Carpenter >> > --- >> > I have 13 more similar places to patch... I'm not totally sure I >> > understand all the issues involved. >> >> What I have done in a similar situation with struct siginfo, is that >> where the structure first appears I have initialized it with memset, >> and then field by field. >> >> Then when the structure is copied I copy the structure with memcpy. >> >> That ensures all of the bytes in the original structure are initialized >> and that all of the bytes are copied. >> >> The goal is to avoid memory that has values of the previous users of >> that memory region from leaking to userspace. Which depending on who >> the previous user of that memory region is could tell userspace >> information about what the kernel is doing that it should not be allowed >> to find out. >> >> I tried to trace through where "info" and thus presumably "info->fix" is >> coming from and only made it as far as register_framebuffer. Given >> that I suspect a local memset, and then a field by field copy right >> before copy_to_user might be a sound solution. But ick. That is a lot >> of fields to copy. > > I know it might sound quite inefficient, but what about making struct > fb_fix_screeninfo __packed? > > This doesn't solve other potential similar issues, but for this > particular case it could be a reasonable and simple fix. It is part of the user space ABI. As such you can't move the fields. Eric From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm@xmission.com (Eric W. Biederman) Date: Wed, 30 Oct 2019 19:26:21 +0000 Subject: Re: [PATCH] fbdev: potential information leak in do_fb_ioctl() Message-Id: <87r22ujaqq.fsf@x220.int.ebiederm.org> List-Id: References: <20191029182320.GA17569@mwanda> <87zhhjjryk.fsf@x220.int.ebiederm.org> <20191030074321.GD2656@xps-13> In-Reply-To: <20191030074321.GD2656@xps-13> (Andrea Righi's message of "Wed, 30 Oct 2019 08:43:21 +0100") MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Andrea Righi Cc: Dan Carpenter , Bartlomiej Zolnierkiewicz , Daniel Vetter , Sam Ravnborg , Maarten Lankhorst , Peter Rosin , Gerd Hoffmann , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, security@kernel.org, Kees Cook , Julia Lawall Andrea Righi writes: > On Tue, Oct 29, 2019 at 02:02:11PM -0500, Eric W. Biederman wrote: >> Dan Carpenter writes: >> >> > The "fix" struct has a 2 byte hole after ->ywrapstep and the >> > "fix = info->fix;" assignment doesn't necessarily clear it. It depends >> > on the compiler. >> > >> > Fixes: 1f5e31d7e55a ("fbmem: don't call copy_from/to_user() with mutex held") >> > Signed-off-by: Dan Carpenter >> > --- >> > I have 13 more similar places to patch... I'm not totally sure I >> > understand all the issues involved. >> >> What I have done in a similar situation with struct siginfo, is that >> where the structure first appears I have initialized it with memset, >> and then field by field. >> >> Then when the structure is copied I copy the structure with memcpy. >> >> That ensures all of the bytes in the original structure are initialized >> and that all of the bytes are copied. >> >> The goal is to avoid memory that has values of the previous users of >> that memory region from leaking to userspace. Which depending on who >> the previous user of that memory region is could tell userspace >> information about what the kernel is doing that it should not be allowed >> to find out. >> >> I tried to trace through where "info" and thus presumably "info->fix" is >> coming from and only made it as far as register_framebuffer. Given >> that I suspect a local memset, and then a field by field copy right >> before copy_to_user might be a sound solution. But ick. That is a lot >> of fields to copy. > > I know it might sound quite inefficient, but what about making struct > fb_fix_screeninfo __packed? > > This doesn't solve other potential similar issues, but for this > particular case it could be a reasonable and simple fix. It is part of the user space ABI. As such you can't move the fields. Eric 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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 22210CA9EC3 for ; Thu, 31 Oct 2019 09:05:46 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id EDC162083E for ; Thu, 31 Oct 2019 09:05:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EDC162083E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=xmission.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=dri-devel-bounces@lists.freedesktop.org Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 2932A6EDF2; Thu, 31 Oct 2019 09:05:20 +0000 (UTC) Received: from out02.mta.xmission.com (out02.mta.xmission.com [166.70.13.232]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8DC916ED35 for ; Wed, 30 Oct 2019 19:26:36 +0000 (UTC) Received: from in01.mta.xmission.com ([166.70.13.51]) by out02.mta.xmission.com with esmtps (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim 4.87) (envelope-from ) id 1iPtby-000758-Jv; Wed, 30 Oct 2019 13:26:30 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=x220.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.87) (envelope-from ) id 1iPtbx-0007ls-C9; Wed, 30 Oct 2019 13:26:30 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Andrea Righi References: <20191029182320.GA17569@mwanda> <87zhhjjryk.fsf@x220.int.ebiederm.org> <20191030074321.GD2656@xps-13> Date: Wed, 30 Oct 2019 14:26:21 -0500 In-Reply-To: <20191030074321.GD2656@xps-13> (Andrea Righi's message of "Wed, 30 Oct 2019 08:43:21 +0100") Message-ID: <87r22ujaqq.fsf@x220.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 X-XM-SPF: eid=1iPtbx-0007ls-C9; ; ; mid=<87r22ujaqq.fsf@x220.int.ebiederm.org>; ; ; hst=in01.mta.xmission.com; ; ; ip=68.227.160.95; ; ; frm=ebiederm@xmission.com; ; ; spf=neutral X-XM-AID: U2FsdGVkX19FbjDNGFR7y0rdUnCUnTTvGuw2gDijzYQ= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCH] fbdev: potential information leak in do_fb_ioctl() X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) X-Mailman-Approved-At: Thu, 31 Oct 2019 09:04:21 +0000 X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-fbdev@vger.kernel.org, security@kernel.org, Kees Cook , Bartlomiej Zolnierkiewicz , kernel-janitors@vger.kernel.org, Daniel Vetter , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Julia Lawall , Gerd Hoffmann , Sam Ravnborg , Peter Rosin , Dan Carpenter Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" Message-ID: <20191030192621.GaBJp-D0AiMgs120sxikZkqxN8yp3L1xSkaewBNbGSY@z> QW5kcmVhIFJpZ2hpIDxhbmRyZWEucmlnaGlAY2Fub25pY2FsLmNvbT4gd3JpdGVzOgoKPiBPbiBU dWUsIE9jdCAyOSwgMjAxOSBhdCAwMjowMjoxMVBNIC0wNTAwLCBFcmljIFcuIEJpZWRlcm1hbiB3 cm90ZToKPj4gRGFuIENhcnBlbnRlciA8ZGFuLmNhcnBlbnRlckBvcmFjbGUuY29tPiB3cml0ZXM6 Cj4+IAo+PiA+IFRoZSAiZml4IiBzdHJ1Y3QgaGFzIGEgMiBieXRlIGhvbGUgYWZ0ZXIgLT55d3Jh cHN0ZXAgYW5kIHRoZQo+PiA+ICJmaXggPSBpbmZvLT5maXg7IiBhc3NpZ25tZW50IGRvZXNuJ3Qg bmVjZXNzYXJpbHkgY2xlYXIgaXQuICBJdCBkZXBlbmRzCj4+ID4gb24gdGhlIGNvbXBpbGVyLgo+ PiA+Cj4+ID4gRml4ZXM6IDFmNWUzMWQ3ZTU1YSAoImZibWVtOiBkb24ndCBjYWxsIGNvcHlfZnJv bS90b191c2VyKCkgd2l0aCBtdXRleCBoZWxkIikKPj4gPiBTaWduZWQtb2ZmLWJ5OiBEYW4gQ2Fy cGVudGVyIDxkYW4uY2FycGVudGVyQG9yYWNsZS5jb20+Cj4+ID4gLS0tCj4+ID4gSSBoYXZlIDEz IG1vcmUgc2ltaWxhciBwbGFjZXMgdG8gcGF0Y2guLi4gIEknbSBub3QgdG90YWxseSBzdXJlIEkK Pj4gPiB1bmRlcnN0YW5kIGFsbCB0aGUgaXNzdWVzIGludm9sdmVkLgo+PiAKPj4gV2hhdCBJIGhh dmUgZG9uZSBpbiBhIHNpbWlsYXIgc2l0dWF0aW9uIHdpdGggc3RydWN0IHNpZ2luZm8sIGlzIHRo YXQKPj4gd2hlcmUgdGhlIHN0cnVjdHVyZSBmaXJzdCBhcHBlYXJzIEkgaGF2ZSBpbml0aWFsaXpl ZCBpdCB3aXRoIG1lbXNldCwKPj4gYW5kIHRoZW4gZmllbGQgYnkgZmllbGQuCj4+IAo+PiBUaGVu IHdoZW4gdGhlIHN0cnVjdHVyZSBpcyBjb3BpZWQgSSBjb3B5IHRoZSBzdHJ1Y3R1cmUgd2l0aCBt ZW1jcHkuCj4+IAo+PiBUaGF0IGVuc3VyZXMgYWxsIG9mIHRoZSBieXRlcyBpbiB0aGUgb3JpZ2lu YWwgc3RydWN0dXJlIGFyZSBpbml0aWFsaXplZAo+PiBhbmQgdGhhdCBhbGwgb2YgdGhlIGJ5dGVz IGFyZSBjb3BpZWQuCj4+IAo+PiBUaGUgZ29hbCBpcyB0byBhdm9pZCBtZW1vcnkgdGhhdCBoYXMg dmFsdWVzIG9mIHRoZSBwcmV2aW91cyB1c2VycyBvZgo+PiB0aGF0IG1lbW9yeSByZWdpb24gZnJv bSBsZWFraW5nIHRvIHVzZXJzcGFjZS4gIFdoaWNoIGRlcGVuZGluZyBvbiB3aG8KPj4gdGhlIHBy ZXZpb3VzIHVzZXIgb2YgdGhhdCBtZW1vcnkgcmVnaW9uIGlzIGNvdWxkIHRlbGwgdXNlcnNwYWNl Cj4+IGluZm9ybWF0aW9uIGFib3V0IHdoYXQgdGhlIGtlcm5lbCBpcyBkb2luZyB0aGF0IGl0IHNo b3VsZCBub3QgYmUgYWxsb3dlZAo+PiB0byBmaW5kIG91dC4KPj4gCj4+IEkgdHJpZWQgdG8gdHJh Y2UgdGhyb3VnaCB3aGVyZSAiaW5mbyIgYW5kIHRodXMgcHJlc3VtYWJseSAiaW5mby0+Zml4IiBp cwo+PiBjb21pbmcgZnJvbSBhbmQgb25seSBtYWRlIGl0IGFzIGZhciBhcyAgcmVnaXN0ZXJfZnJh bWVidWZmZXIuICBHaXZlbgo+PiB0aGF0IEkgc3VzcGVjdCBhIGxvY2FsIG1lbXNldCwgYW5kIHRo ZW4gYSBmaWVsZCBieSBmaWVsZCBjb3B5IHJpZ2h0Cj4+IGJlZm9yZSBjb3B5X3RvX3VzZXIgbWln aHQgYmUgYSBzb3VuZCBzb2x1dGlvbi4gIEJ1dCBpY2suICBUaGF0IGlzIGEgbG90Cj4+IG9mIGZp ZWxkcyB0byBjb3B5Lgo+Cj4gSSBrbm93IGl0IG1pZ2h0IHNvdW5kIHF1aXRlIGluZWZmaWNpZW50 LCBidXQgd2hhdCBhYm91dCBtYWtpbmcgc3RydWN0Cj4gZmJfZml4X3NjcmVlbmluZm8gX19wYWNr ZWQ/Cj4KPiBUaGlzIGRvZXNuJ3Qgc29sdmUgb3RoZXIgcG90ZW50aWFsIHNpbWlsYXIgaXNzdWVz LCBidXQgZm9yIHRoaXMKPiBwYXJ0aWN1bGFyIGNhc2UgaXQgY291bGQgYmUgYSByZWFzb25hYmxl IGFuZCBzaW1wbGUgZml4LgoKSXQgaXMgcGFydCBvZiB0aGUgdXNlciBzcGFjZSBBQkkuICBBcyBz dWNoIHlvdSBjYW4ndCBtb3ZlIHRoZSBmaWVsZHMuCgpFcmljCl9fX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fCmRyaS1kZXZlbCBtYWlsaW5nIGxpc3QKZHJpLWRl dmVsQGxpc3RzLmZyZWVkZXNrdG9wLm9yZwpodHRwczovL2xpc3RzLmZyZWVkZXNrdG9wLm9yZy9t YWlsbWFuL2xpc3RpbmZvL2RyaS1kZXZlbA==