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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4172BC04A95 for ; Sun, 25 Sep 2022 11:58:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231176AbiIYL6A (ORCPT ); Sun, 25 Sep 2022 07:58:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231511AbiIYL5y (ORCPT ); Sun, 25 Sep 2022 07:57:54 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.17.22]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5A7C32C112 for ; Sun, 25 Sep 2022 04:57:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1664107067; bh=2acJ5q54HwjpL+Cam55Jrx3R3x2p2oTERxijPz0cUl4=; h=X-UI-Sender-Class:Date:Subject:To:Cc:References:From:In-Reply-To; b=gsIYSjTFNjmflB/F04z1XhpVqsToLXVKER98TXAcUJl82DjXq1eJQdaQurCd/e2YM spFLwYkl9lsEEbsXWTfwmbvGdHtyEop9cfkuXN2jOlNLBG32lEPGyLHMX5vjkfA+Rr xJbP4Zqtfb6Gm8iOo2DbKlmsyH2lv5aSNqIcT3R4= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [192.168.20.60] ([92.116.188.118]) by mail.gmx.net (mrgmx104 [212.227.17.168]) with ESMTPSA (Nemesis) id 1MQe5u-1orDrA3PGg-00NmJO; Sun, 25 Sep 2022 13:57:46 +0200 Message-ID: Date: Sun, 25 Sep 2022 13:57:46 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.3.0 Subject: Re: [PATCH] video: fbdev: smscufx: Fix use-after-free in ufx_ops_open() Content-Language: en-US To: Hyunwoo Kim , steve.glendinning@shawell.net Cc: linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org References: <20220925110329.GA380036@ubuntu> From: Helge Deller In-Reply-To: <20220925110329.GA380036@ubuntu> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:6Pvq6jJ4u17R1dbuy5/Xo1j11QgOouG6DpEYQLOIaV8lJZFs4KK n2txJ5rX2WkGwLsLOWdBHldyCiH1XO8fMoGPBN3r5riJGWjx/IH2PpE9Ydu6vNyb8kgY78a iXlnfrVapKoazZY5BGM1m0FINKx5+wyDSQtoTBhICL+qnxHSNbM5n9tgVPhzFSH8Ne9Tr7I ULMwonIqAH8XAEyXDL8WQ== X-UI-Out-Filterresults: notjunk:1;V03:K0:xLuj2YrM9CM=:HANclgzyl3Y1jSgQqVGitu OEBbrh9CuzoTDlp5RNfmVLVvqByJNUGLKcoJ+iC5elKyDincFbwZllWvgE/q+Ai9O1qJaJ2RM 5oDi1Dk2LqPHaTQzhGdbew6HRuVH7YidDjBmwrUJGzs3ocqk3lfjqHj2rvGEINJm8w6HeKJ+j IIjm+xQUuLTAxoC3+WuP9SuYjGBg4rO59s98QcGIhEXSG0MiXr/pf+L0Gg28tmLkVA+J7hINI Oh5I6Wm3lPdzV/gKfk54yjEH9l40PkNaqD/lr+1TWOTGyBTWymL7AaoCwrSZxFFcsQipC5Tox uCOVo4gP5oLLxnNG3XFYlKcvZ2CjhXZaCrlLOJTJIjqsLLKo3r6vmSKjNRGe3fiY7XYKfSTg9 RBYkR0eSvq384HoropoPVxyKjU78DFWLPPjumDpp9kFpzInpNJV0wR6DpO5Nu1pV7BmvxrvCD 1LMyFUrot0k6ur+KCowA5YpicVPVI+blMGbV6t2xIAzeHHQ3yn6RZAejw9ukhPE3vls++1FPF zWsfx45SG/R6xkIFFoAqA1orUrBoNBeaBMgq6VhFaoepwNifnDVoLbW8muW/yxX7N4a73OOze MkzRP9dtMov6Ez6QpE6gTVjqLkAlN3uq9XMB9/fN/cUljyB/EqjvuVY8Rll6H49GZ/K6W4ghE uufhfj1VGDPh+ijoKTorx1epy73hcUD3rNphi3Hy77UmJgekZAJpkUGHl4bNX8SVhDxirDyVF xGiRKIurr+tozGKU+IbXxOUp4j4d4D61DYGmIpi7s4C7AxcBb8Ff7xv2QmKE9QvUbuakhDeBs 9aJEQIrK/c2PaKUfC/LDiuR5UiVVzkKqONRbLSvjNUCO7hmfXCG3UXv76D56g6OJ+e8MmAf01 OV/E/PCc7wN0gap+xNb3yxEH8giDwfGp1RNQ1P4d1cZ0hODHzg0FQOqXE7EbaKPAyxB0Q1wwD EyJyTpBGF985K01viHKG7BXZnwWYRx7q1RAKjuraM7S75n+aQpJABD1jLIeXERg7+FwAfcLpN nYi4Y5xArcnmuY0Cqqm4QJHSM80ZOGTPfxtZ5KhAqlOLr1ULZj+eGKALoE46Cc7n5F6qbEkrc n2xkKRV8RKs2JmapKhe6J65N58CiI5OSAzco5+AQnitP6XHbLR55J4bMTajtDIA07VOVeDtdQ lZP6cikdi4rduYgQc46kogvwND Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org On 9/25/22 13:03, Hyunwoo Kim wrote: > A race condition may occur if the user physically removes the > USB device while calling open() for this device node. > > This is a race condition between the ufx_ops_open() function and > the ufx_usb_disconnect() function, which may eventually result in UAF. > > So, add a mutex to the ufx_ops_open() and ufx_usb_disconnect() functions > to avoid race contidion of krefs. > > Signed-off-by: Hyunwoo Kim > --- > drivers/video/fbdev/smscufx.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) > > diff --git a/drivers/video/fbdev/smscufx.c b/drivers/video/fbdev/smscufx= .c > index d7aa5511c361..a4378a7241f7 100644 > --- a/drivers/video/fbdev/smscufx.c > +++ b/drivers/video/fbdev/smscufx.c > @@ -1065,6 +1067,8 @@ static int ufx_ops_open(struct fb_info *info, int = user) > { > struct ufx_data *dev =3D info->par; > > + mutex_lock(&disconnect_mutex); > + The next few lines show: if (user =3D=3D 0 && !console) return -EBUSY; in this case this function exits with the mutex held. Please check all possible exit paths and unlock the mutex where necessary. Helge