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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 36D5EC433F5 for ; Mon, 20 Sep 2021 18:14:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C58F613CE for ; Mon, 20 Sep 2021 18:14:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1376861AbhITSOw (ORCPT ); Mon, 20 Sep 2021 14:14:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:33074 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1358692AbhITSH0 (ORCPT ); Mon, 20 Sep 2021 14:07:26 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EE88663255; Mon, 20 Sep 2021 17:18:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1632158310; bh=PX2xQm/C4MK4PU4j7gsqvgYGjt7b7XdaBqs4CaQJ+Bo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SUIXveFc6javHF7hf+//q6KyGroMQWyD9gsRFFL7dgDV04W6oTGmZVh/wqk36+WMl U5hnjCafJOgagmOjvAR6BefibEgqtfdXnZPWgUqbSKkURFV3znMuSyhJp9VQwBn3Y5 vao4+aNi7fJDWpGemsooFW13XmYGA6IHVCoECoOA= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Zheyu Ma , Sam Ravnborg , Sasha Levin Subject: [PATCH 5.4 098/260] video: fbdev: asiliantfb: Error out if pixclock equals zero Date: Mon, 20 Sep 2021 18:41:56 +0200 Message-Id: <20210920163934.464848684@linuxfoundation.org> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20210920163931.123590023@linuxfoundation.org> References: <20210920163931.123590023@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zheyu Ma [ Upstream commit b36b242d4b8ea178f7fd038965e3cac7f30c3f09 ] 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 first. The following log reveals it: [ 43.861711] divide error: 0000 [#1] PREEMPT SMP KASAN PTI [ 43.861737] CPU: 2 PID: 11764 Comm: i740 Not tainted 5.14.0-rc2-00513-gac532c9bbcfb-dirty #224 [ 43.861756] RIP: 0010:asiliantfb_check_var+0x4e/0x730 [ 43.861843] Call Trace: [ 43.861848] ? asiliantfb_remove+0x190/0x190 [ 43.861858] fb_set_var+0x2e4/0xeb0 [ 43.861866] ? fb_blank+0x1a0/0x1a0 [ 43.861873] ? lock_acquire+0x1ef/0x530 [ 43.861884] ? lock_release+0x810/0x810 [ 43.861892] ? lock_is_held_type+0x100/0x140 [ 43.861903] ? ___might_sleep+0x1ee/0x2d0 [ 43.861914] ? __mutex_lock+0x620/0x1190 [ 43.861921] ? do_fb_ioctl+0x313/0x700 [ 43.861929] ? mutex_lock_io_nested+0xfa0/0xfa0 [ 43.861936] ? __this_cpu_preempt_check+0x1d/0x30 [ 43.861944] ? _raw_spin_unlock_irqrestore+0x46/0x60 [ 43.861952] ? lockdep_hardirqs_on+0x59/0x100 [ 43.861959] ? _raw_spin_unlock_irqrestore+0x46/0x60 [ 43.861967] ? trace_hardirqs_on+0x6a/0x1c0 [ 43.861978] do_fb_ioctl+0x31e/0x700 Signed-off-by: Zheyu Ma Signed-off-by: Sam Ravnborg Link: https://patchwork.freedesktop.org/patch/msgid/1627293835-17441-2-git-send-email-zheyuma97@gmail.com Signed-off-by: Sasha Levin --- drivers/video/fbdev/asiliantfb.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/video/fbdev/asiliantfb.c b/drivers/video/fbdev/asiliantfb.c index ea31054a28ca..c1d6e6336225 100644 --- a/drivers/video/fbdev/asiliantfb.c +++ b/drivers/video/fbdev/asiliantfb.c @@ -227,6 +227,9 @@ static int asiliantfb_check_var(struct fb_var_screeninfo *var, { unsigned long Ftarget, ratio, remainder; + if (!var->pixclock) + return -EINVAL; + ratio = 1000000 / var->pixclock; remainder = 1000000 % var->pixclock; Ftarget = 1000000 * ratio + (1000000 * remainder) / var->pixclock; -- 2.30.2