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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS 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 1BE29C282CE for ; Tue, 4 Jun 2019 12:54:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E953923A79 for ; Tue, 4 Jun 2019 12:54:48 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="exCfEpz0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727801AbfFDMyp (ORCPT ); Tue, 4 Jun 2019 08:54:45 -0400 Received: from mail-vs1-f66.google.com ([209.85.217.66]:44749 "EHLO mail-vs1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727394AbfFDMyo (ORCPT ); Tue, 4 Jun 2019 08:54:44 -0400 Received: by mail-vs1-f66.google.com with SMTP id v129so4146747vsb.11; Tue, 04 Jun 2019 05:54:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=I8kO1ihPctG1ALoFxeAqn+bcx97sgjF7Igmu2hN3Q44=; b=exCfEpz0aDM5HyM575FloA/YfJ++ceTkjCpBJK2XDsYT/gpO2+xGgJndeT0AC/ht2a wkNEotuLchAUzVIFK7e3lM3C+vWW6sEG7IqujCq+/qH/Gbi7xOmh5DpnIG33JQKDsylf 60g9fz5sTCU66lDj5+XCOUVOSZr41pY18POyyahHIId6UN8/9M0jgMFvQMDneojjaOiE 1L6LO96oyRw1vaFQSbapW/Gfo/sf3sUry+QLeNLqi162T7LbdR4a/J9kVlIeUS0RLo8o AV3bk6hO5+vbLl/bDW0Gx0mDrVu3P080n4+1E2VT7yhIvh6cBtympMYd4vtxvUywvUZw TGwQ== 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=I8kO1ihPctG1ALoFxeAqn+bcx97sgjF7Igmu2hN3Q44=; b=UIadTNvFk/uGjFWyb38afnPRFXA0BZGZVVxXMY9g2XW9rrKU9vDjSahrcT/i0jG+V7 535WmB6yAXplosgWTtURlEiTXRTcVbwIwHjSaYkJERLfnz1eFRELDiif1K939qQ9Kgtj I1XQbMMz0sDFEL6Mk03veilZKNuDZqNG6tUPG2yHpP94dl/CHIRW2TxD0d5A8jl8Hvly JIVQNaui+w5wrP0/xju4obfcxb1bcL9RCOIov69R3nxItwneIrsJHAkfgWu3lLdogHF8 vs2/jWR1svullARXQSHajVDa9N8TcmpV+Z6YUWWhHWP+1bchL74SPSxg/OMGw2ttTtb9 x4zQ== X-Gm-Message-State: APjAAAWseRT2vZ3drI/gPFHYLAfeMzFPBXwqI9GsogA2Kps+Pax2LRxc 0TWMmpu7/QxEYXDAl2FWMkw5YSGIQHjT/sfzEWI= X-Google-Smtp-Source: APXvYqzU2dVgdxzCtI1Ajw8zYy3APA2LeWIn9GRpeCCU4Pvxi/E5TV+54X0G2v27ha80GXHttClSXmmRzeaSXyhw34c= X-Received: by 2002:a67:cd14:: with SMTP id u20mr737938vsl.36.1559652883964; Tue, 04 Jun 2019 05:54:43 -0700 (PDT) MIME-Version: 1.0 References: <1559651505-18137-1-git-send-email-92siuyang@gmail.com> In-Reply-To: From: Yang Xiao <92siuyang@gmail.com> Date: Tue, 4 Jun 2019 20:54:02 +0800 Message-ID: Subject: Re: [PATCH] net: compat: fix msg_controllen overflow in scm_detach_fds_compat() To: Daniel Borkmann Cc: David Miller , netdev , LKML , Eric Dumazet Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, Jun 4, 2019 at 8:46 PM Daniel Borkmann wrote: > > On 06/04/2019 02:31 PM, Young Xiao wrote: > > There is a missing check between kmsg->msg_controllen and cmlen, > > which can possibly lead to overflow. > > > > This bug is similar to vulnerability that was fixed in commit 6900317f5eff > > ("net, scm: fix PaX detected msg_controllen overflow in scm_detach_fds"). > > Back then I mentioned in commit 6900317f5eff: > > In case of MSG_CMSG_COMPAT (scm_detach_fds_compat()), I haven't seen an > issue in my tests as alignment seems always on 4 byte boundary. Same > should be in case of native 32 bit, where we end up with 4 byte boundaries > as well. > > Do you have an actual reproducer or is it based on code inspection? based on inspection. > > > Signed-off-by: Young Xiao <92siuyang@gmail.com> > > --- > > net/compat.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/net/compat.c b/net/compat.c > > index a031bd3..8e74dfb 100644 > > --- a/net/compat.c > > +++ b/net/compat.c > > @@ -301,6 +301,8 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm) > > err = put_user(cmlen, &cm->cmsg_len); > > if (!err) { > > cmlen = CMSG_COMPAT_SPACE(i * sizeof(int)); > > + if (kmsg->msg_controllen < cmlen) > > + cmlen = kmsg->msg_controllen; > > kmsg->msg_control += cmlen; > > kmsg->msg_controllen -= cmlen; > > } > > > -- Best regards! Young -----------------------------------------------------------