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 2988EC76196 for ; Wed, 22 Mar 2023 20:03:03 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 167EE10EA16; Wed, 22 Mar 2023 20:03:02 +0000 (UTC) Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by gabe.freedesktop.org (Postfix) with ESMTPS id CC0DA10EA16 for ; Wed, 22 Mar 2023 20:02:59 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 73BDCB81DED; Wed, 22 Mar 2023 20:02:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24940C433EF; Wed, 22 Mar 2023 20:02:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679515377; bh=6rJG97ZzxVmIyk1bTkmXt1OfZk0tUqXxGyQT7Wn+4hM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=CuWjr3IWgd5Qn6+rkTgw4vBhI2+14VZDEV9GmTBvRNcIpS/lKvJWsauNfwKHGfzyQ TLM5Fa769G4ff6Zjz7TOTUwP3Vu6xk8Kz2NU3OpW5dJ1DTT0iRFQKJugcHRJ5qJZrf 3ipAoxXFj5QD335Yv5UXlr+K9oc5LvyPXkGLddqQkZreIK890kgqss086Lv/UvVOY0 SBQTRSlptm7aGYTwO5qxA5p4Jk1RiFd3kSbjKA38lpwdsk4ONe9JuXoo7dFWsDp6TP IsXwyjy5DnNRjrbitvrTO9FtQqyo2Li9RgMLnmUY84qRqiyTNhRcNRck8HKL1inQKC cL3f93tlO3m3w== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH AUTOSEL 5.4 4/9] fbdev: tgafb: Fix potential divide by zero Date: Wed, 22 Mar 2023 16:02:36 -0400 Message-Id: <20230322200242.1997527-4-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322200242.1997527-1-sashal@kernel.org> References: <20230322200242.1997527-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit 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: Sasha Levin , linux-fbdev@vger.kernel.org, Helge Deller , javierm@redhat.com, dri-devel@lists.freedesktop.org, Wei Chen , wsa+renesas@sang-engineering.com, tzimmermann@suse.de Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Wei Chen [ Upstream commit f90bd245de82c095187d8c2cabb8b488a39eaecc ] fb_set_var would by called when user invokes ioctl with cmd FBIOPUT_VSCREENINFO. User-provided data would finally reach tgafb_check_var. In case var->pixclock is assigned to zero, divide by zero would occur when checking whether reciprocal of var->pixclock is too high. Similar crashes have happened in other fbdev drivers. There is no check and modification on var->pixclock along the call chain to tgafb_check_var. We believe it could also be triggered in driver tgafb from user site. Signed-off-by: Wei Chen Signed-off-by: Helge Deller Signed-off-by: Sasha Levin --- drivers/video/fbdev/tgafb.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/video/fbdev/tgafb.c b/drivers/video/fbdev/tgafb.c index 286b2371c7dd3..eab2b4f87d68f 100644 --- a/drivers/video/fbdev/tgafb.c +++ b/drivers/video/fbdev/tgafb.c @@ -166,6 +166,9 @@ tgafb_check_var(struct fb_var_screeninfo *var, struct fb_info *info) { struct tga_par *par = (struct tga_par *)info->par; + if (!var->pixclock) + return -EINVAL; + if (par->tga_type == TGA_TYPE_8PLANE) { if (var->bits_per_pixel != 8) return -EINVAL; -- 2.39.2