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=-3.7 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 6E065C4741F for ; Sun, 27 Sep 2020 12:06:51 +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 D989823976 for ; Sun, 27 Sep 2020 12:06:50 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="MhENV1Hh" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D989823976 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linuxfoundation.org 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 075FD6E0C5; Sun, 27 Sep 2020 12:06:50 +0000 (UTC) Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6A7B06E0C5 for ; Sun, 27 Sep 2020 12:06:48 +0000 (UTC) Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 79D8D2389F; Sun, 27 Sep 2020 12:06:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601208408; bh=QHcjNHJZuDxl5EUnjYYZQunEgwhM8w3ezdc49mZGgGk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MhENV1HhflQPaxWUfLAnc6xTsItA6RXILvigXqyJWPKkbFAPMCkJVMaX0LMBGtxDv VD10aaV577rK1wy6dsfF2VGujJnB9EOtOtdyar0yJntRwOhsLxPrgL/pFy8cydevtl lKU4Nn3veJpPIIJWbfngaBgZCLwMidu1oEsDhDbI= Date: Sun, 27 Sep 2020 14:06:58 +0200 From: Greg KH To: Tetsuo Handa Subject: Re: [PATCH] vt_ioctl: make VT_RESIZEX behave like VT_RESIZE Message-ID: <20200927120658.GA107433@kroah.com> References: <000000000000226d3f05b02dd607@google.com> <47907f77-b14b-b433-45c6-a315193f0c1a@i-love.sakura.ne.jp> <494395bc-a7dd-fdb1-8196-a236a266ef54@i-love.sakura.ne.jp> <20200927092701.GA1037755@PWN> <4933b81b-9b1a-355b-df0e-9b31e8280ab9@i-love.sakura.ne.jp> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <4933b81b-9b1a-355b-df0e-9b31e8280ab9@i-love.sakura.ne.jp> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: syzbot , linux-fbdev@vger.kernel.org, George Kennedy , b.zolnierkie@samsung.com, daniel.vetter@ffwll.ch, deller@gmx.de, syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, Linus Torvalds , jirislaby@kernel.org, Peilin Ye Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Sun, Sep 27, 2020 at 08:46:30PM +0900, Tetsuo Handa wrote: > syzbot is reporting UAF/OOB read at bit_putcs()/soft_cursor() [1][2], for > vt_resizex() from ioctl(VT_RESIZEX) allows setting font height larger than > actual font height calculated by con_font_set() from ioctl(PIO_FONT). > Since fbcon_set_font() from con_font_set() allocates minimal amount of > memory based on actual font height calculated by con_font_set(), > use of vt_resizex() can cause UAF/OOB read for font data. > > VT_RESIZEX was introduced in Linux 1.3.3, but it is unclear that what > comes to the "+ more" part, and I couldn't find a user of VT_RESIZEX. > > #define VT_RESIZE 0x5609 /* set kernel's idea of screensize */ > #define VT_RESIZEX 0x560A /* set kernel's idea of screensize + more */ > > So far we are not aware of syzbot reports caused by setting non-zero value > to v_vlin parameter. But given that it is possible that nobody is using > VT_RESIZEX, we can try removing support for v_clin and v_vlin parameters. Debian code search doesn't show any users, and that's usually a good indication of what userspace ioctls for old things like this, are being used for. So this makes sense to me, I'll queue it up, thanks! greg k-h _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel