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=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, T_DKIMWL_WL_MED,USER_IN_DEF_DKIM_WL autolearn=unavailable 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 8275BC433EF for ; Fri, 15 Jun 2018 16:45:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2936C208B2 for ; Fri, 15 Jun 2018 16:45:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="SN2d/mxJ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2936C208B2 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.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 S966078AbeFOQpF (ORCPT ); Fri, 15 Jun 2018 12:45:05 -0400 Received: from mail-oi0-f66.google.com ([209.85.218.66]:38891 "EHLO mail-oi0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S964992AbeFOQpD (ORCPT ); Fri, 15 Jun 2018 12:45:03 -0400 Received: by mail-oi0-f66.google.com with SMTP id d5-v6so9356721oib.5 for ; Fri, 15 Jun 2018 09:45:03 -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=MEFaJhiXyNan8nBVc3ywGNwatyQN9rFssV/TKLDuqis=; b=SN2d/mxJ2goYBb70AhMmblYACvAkaFLsSlBc2ZhM5cyb+JhB9gJAwQV8Kz8NOdUlrI o1degSL5cPf5wJOETaOEV2bCVBfIyEqiSxGjclXdfxDsaOsgdPy2Ae4MupYWRyoPJqJ7 uFAmzybxDYx4ODqQxNLO0QlWmhhaTdx+bwtlqaZl1iD5MJjO7Y0W3szVk8s0nNsyClFR BH2Ipu0pzuLlwy9W+jF/Sn1YehLQ6kp6Pwo+rnO9+nX2Fbqae7VuPLm6iIBQfHq6YMvO zkx6FWcl+sAlJaTeRshwrgsjsrVQcYVHvYEjXbVIIV5HKSPQ9wDc/Uu8unw7Bi9ArpKj pURg== 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=MEFaJhiXyNan8nBVc3ywGNwatyQN9rFssV/TKLDuqis=; b=EJv8r2WiMpHLnKJZCkOuHyXiDRJIIGsWZ5V96PgLiD58gtDRlain2LNdjnrqE+DUXm IcXam2WQgCwMNFvn66HHejPS3T8LQNvd64PunJXhoIm/JSzOFN9+Cvim9+oZSiDcp6sv 9d1O8/XVLYfo7aiF06O17lg+q/yYpAOz+LvGsKpDZR7XFr700F97rO9Y0qbR8oteDHBH k6P9XgYCqJt04ihpnUjnF0WAp3cGFbek3yQZBHZ18Y7Ud35fzKX9qXaRh1nTboGTDypf 3NzPOun/tNzbAjRW80mqA/IXkY7BZyuq/kKuePriZ6WTCh9hgTn7CvnxCqioMVQ7OPe8 hjaw== X-Gm-Message-State: APt69E0plGWWF/1x0YR/irdQW3IHgcZ3x3Lz91RqmI+ShVqGyWqquTuD gh4Bzco7JEA2FzjDBdVunBDcWPCiUcT+eVpjAh0YoA== X-Google-Smtp-Source: ADUXVKLBAlbs3rze3jgXzRNYgEIXnR0XfjQtCHZSOKBCwoPpYtRRQjd3pEG9GqMtTJiPVQMIbG+HUwDsnOOTcBCWE1Y= X-Received: by 2002:aca:6b03:: with SMTP id g3-v6mr1211431oic.219.1529081102715; Fri, 15 Jun 2018 09:45:02 -0700 (PDT) MIME-Version: 1.0 References: <20180615152335.208202-1-jannh@google.com> <20180615164009.GD30522@ZenIV.linux.org.uk> In-Reply-To: <20180615164009.GD30522@ZenIV.linux.org.uk> From: Jann Horn Date: Fri, 15 Jun 2018 18:44:51 +0200 Message-ID: Subject: Re: [PATCH] sg, bsg: mitigate read/write abuse, block uaccess in release To: Al Viro Cc: axboe@kernel.dk, fujita.tomonori@lab.ntt.co.jp, dgilbert@interlog.com, jejb@linux.vnet.ibm.com, martin.petersen@oracle.com, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, kernel list , Kernel Hardening , security@kernel.org Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jun 15, 2018 at 6:40 PM Al Viro wrote: > > On Fri, Jun 15, 2018 at 05:23:35PM +0200, Jann Horn wrote: > > > I've mostly copypasted ib_safe_file_access() over as > > scsi_safe_file_access() because I couldn't find a good common header - > > please tell me if you know a better way. > > The duplicate pr_err_once() calls are so that each of them fires once; > > otherwise, this would probably have to be a macro. > > > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") > > Cc: > > Signed-off-by: Jann Horn > > --- > > WTF do you mean, in ->release()? That makes no sense whatsoever - > what kind of copy_{to,from}_user() would be possible in there? bsg_release -> bsg_put_device -> bsg_complete_all_commands -> blk_complete_sgv4_hdr_rq -> bsg_scsi_complete_rq -> copy_to_user. I don't think that was intentional. Basically, the sense buffer is copied to a userspace address supplied in the previous ->write() when you ->read() the reply. But when you ->release() the file without reading the reply, they have to clean it up, and for that, they reuse the same code they use for ->read() - so the sense buffer is written to userspace on ->release().