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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 109DBC4332F for ; Thu, 9 Sep 2021 13:11:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F1505611B0 for ; Thu, 9 Sep 2021 13:11:12 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1353025AbhIINMU (ORCPT ); Thu, 9 Sep 2021 09:12:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:42452 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355948AbhIINBD (ORCPT ); Thu, 9 Sep 2021 09:01:03 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 3553C61411; Thu, 9 Sep 2021 11:59:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1631188763; bh=PX2xQm/C4MK4PU4j7gsqvgYGjt7b7XdaBqs4CaQJ+Bo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E23M6esqbSVDQIaRUWgWHZftssDGy9CL5xDJKT/KUPXRwC2zcsMc0ioP31/QjvTab w6sKxYOXQjgt4+BCoBe0Qcbb+7Ion6aRd6EF038sdujEn4p4aWOM18cyxWU3ca1fhT B0XAJNFKe/Rqu6EdJ+0rNchXvFKxZZEAYeqfd/2lXf5Rzv345utP6EQYxudsE5wDdm GZyGLZgJzlkjxWBuy910jx54eQwr9wee2B/40Dg4iiFc4JckZ6vQjWR/Myzla63QIc LPkZTCovhiJtq31Amuw1CfvdbVThRNjz6L5+hWCRZxGjmTP3X0jgnTp4s1gHRprUjE lOJ49WuUjLmlg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Zheyu Ma , Sam Ravnborg , Sasha Levin , dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org Subject: [PATCH AUTOSEL 4.14 17/59] video: fbdev: asiliantfb: Error out if 'pixclock' equals zero Date: Thu, 9 Sep 2021 07:58:18 -0400 Message-Id: <20210909115900.149795-17-sashal@kernel.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210909115900.149795-1-sashal@kernel.org> References: <20210909115900.149795-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@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