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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 0C2A0C433EF for ; Mon, 11 Apr 2022 06:19:59 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 1D17A10ED2F; Mon, 11 Apr 2022 06:19:59 +0000 (UTC) Received: from mout.gmx.net (mout.gmx.net [212.227.15.18]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6CA4B10E974 for ; Mon, 11 Apr 2022 06:19:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.net; s=badeba3b8450; t=1649657995; bh=sfEMxueHlINxP3Ft9h3uCgQL3x0NL57EBnCByLr9WHw=; h=X-UI-Sender-Class:Date:Subject:To:Cc:References:From:In-Reply-To; b=LXG4o5IDHO3ef5fr2tCKvvAdmWy6WIOep7bK3zPAw1v0pOte4O2KeD1jEN7hX5ct4 IcwhR6sh4VZBXqQfqgaSM9+8BW5vCFjVtyaGLZZVttgDs/8q7oGwGLU+PTHciFrDh2 adcuO0ETsyF73Pz5sk0MlqsJzWhDmnmrfh/Fm57M= X-UI-Sender-Class: 01bb95c1-4bf8-414a-932a-4f6e2808ef9c Received: from [192.168.20.60] ([92.116.145.57]) by mail.gmx.net (mrgmx005 [212.227.17.190]) with ESMTPSA (Nemesis) id 1MvK0R-1nuukM0DMv-00rHOG; Mon, 11 Apr 2022 08:19:55 +0200 Message-ID: Date: Mon, 11 Apr 2022 08:18:09 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Subject: Re: [PATCH 1/7] video: fbdev: i740fb: Error out if 'pixclock' equals zero Content-Language: en-US To: Ondrej Zary , Zheyu Ma References: <20220404084723.79089-1-zheyuma97@gmail.com> <202204101102.13505.linux@zary.sk> From: Helge Deller In-Reply-To: <202204101102.13505.linux@zary.sk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:7UMRgaQGw+lmVxgdw35JNxFmQ8/erZc7B2ZAznUL56KFExbyAyL eozhZDqrTS640g+EG/wkbxyUl8tATZwLYGBClGzFD5kDMy1zVp8ncsOPrHKCShmztq59eXl 43nNT+8gxU1B2smqyyhJrXqFFnQ5TDJsLNhcWI8Uh+nsFWnporQ37jdkOTraCUBwf05DeQm egEJBdtNlJbsWoNHbWn6w== X-UI-Out-Filterresults: notjunk:1;V03:K0:wz+exaJD4EU=:qCbHUBMR0eECdtBeg75SJM U4Thoi+oZ8fwwOrWoG2hwwJ07nadK6Jm03W7VVGxZEYRgPFh1iZpPDRgvRM4S1oB+TVrN9IvV 2B/S4Lm21lqV9vwhXQK66Xc2YQjR6DxQkm+FeMVWdsOFDjTS7G+UwlxQB0NRUQ6h0s5oHTTkp n5U9MdMRoHHf/JfpRgPLBvCb55hXzHbbI6NmoZFjCjTuJe+eglBElNT0Eowp/LxqMnkWwoPjA 8osGq39Rah3GpUONk5awjJHiR0pe8C1iesARwQNu42byJ9Nmip0nh+CD0XtGK/VnPiEEPdPeO yEINGfEAHdyYvn8ccLQjcA/JSZMDulF9dLFb2iKZfw7cYuKkmsOQrvCseLVzAESqVhX1vCM3L /FmPOOKieZ+6bzZPYAV/+OvsyHCjCTaKtv44feUrok68MrLiZZCGGzva5twG/e7uq+PW+hx0O xdnlq8hgdkIYmK+BJaubWb097/CLjtgw4jSbVfq+yuEQiT0GwaWTGHSJVRtcUDANHqLwv0h7q x1D+bzOomHGx8kmiP5uPq4zNlDBrhfAtNBuUQGj9gbIsLdyZnz1tjRBDdCUWvSisNnY0B8eE+ 6Pmq4EUmauZY5MlJX/4iY5w1vaBC6pzHjVqf35fQ+S/6aJtDqeRfa0Nx69h+K86yhJYH+A2sA +/QN+JQ6a1q19QElMcOywTVCoJ3AM25ThZ2RZ16wm9/km/K0wzAeSwgpa+Z/iQ7YIokH6hu0j Gw4Dpl8Kc1PBaWHrLjfiSDOqjP3gpgZL13w6YCXxx9j9d7qhHvkvPDYnyneSiMxwVCxMCfaw9 Yiri1Y6qZK/6IFrCN/bMuipbcuCY0YGu2/QUgAo8CJ663SYVSIgXH0cL8A/E+uqCm1pO+shqM MTAWAP0JDcXSgUWFJsEuZqigyKLSLudz+57FTgBGqa25uA432PzWSgdJEoEPFG0eAJq6JT+UH 98pFXzf3KPz4EK5SrFBm8/CICP60rHasqehg7bFe+VWjJXWONFwdcXUM2zNkLUKj2hy4rxMaj hCO6AlqijlgG+syyV4ATSMQ+NlLKZ9t3qfSu+PGqucClxai+BNEoqpVuk8noaVYKyCKBV76Bi iV/iWoQhb/7Iw0= 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: Linux Fbdev development list , Linux Kernel Mailing List , DRI Development Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 4/10/22 11:02, Ondrej Zary wrote: > On Friday 08 April 2022 03:58:10 Zheyu Ma wrote: >> On Fri, Apr 8, 2022 at 3:50 AM Helge Deller wrote: >>> >>> On 4/4/22 10:47, Zheyu Ma wrote: >>>> The userspace program could pass any values to the driver through >>>> ioctl() interface. If the driver doesn't check the value of 'pixclock= ', >>>> it may cause divide error. >>>> >>>> Fix this by checking whether 'pixclock' is zero in the function >>>> i740fb_check_var(). >>>> >>>> The following log reveals it: >>>> >>>> divide error: 0000 [#1] PREEMPT SMP KASAN PTI >>>> RIP: 0010:i740fb_decode_var drivers/video/fbdev/i740fb.c:444 [inline] >>>> RIP: 0010:i740fb_set_par+0x272f/0x3bb0 drivers/video/fbdev/i740fb.c:7= 39 >>>> Call Trace: >>>> fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1036 >>>> do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1112 >>>> fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1191 >>>> vfs_ioctl fs/ioctl.c:51 [inline] >>>> __do_sys_ioctl fs/ioctl.c:874 [inline] >>>> >>>> Signed-off-by: Zheyu Ma >>> >>> Hello Zheyu, >>> >>> I've applied the patches #2-#7 of this series, but left >>> out this specific patch (for now). >>> As discussed on the mailing list we can try to come up with a >>> better fix (to round up the pixclock when it's invalid). >>> If not, I will apply this one later. >> >> I'm also looking forward to a more appropriate patch for this driver! > > I was not able to reproduce it at first but finally found it: the > monitor must be unplugged. If a valid EDID is present, > fb_validate_mode() call in i740fb_check_var() will refuse zero > pixclock. > > Haven't found any obvious way to correct zero pixclock value. Most other= drivers simply return -EINVAL. Thanks for checking, Ondrej! So, I'll apply the EINVAL-patch from Zheyu for now. Helge