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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 22D71C6FD1F for ; Wed, 22 Mar 2023 20:08:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231768AbjCVUIH (ORCPT ); Wed, 22 Mar 2023 16:08:07 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51002 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231823AbjCVUHo (ORCPT ); Wed, 22 Mar 2023 16:07:44 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 625FD74DFA; Wed, 22 Mar 2023 13:01:50 -0700 (PDT) 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 dfw.source.kernel.org (Postfix) with ESMTPS id BBE0D62294; Wed, 22 Mar 2023 20:00:57 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38EF1C433EF; Wed, 22 Mar 2023 20:00:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679515257; bh=Y6BakBa9UYvIosItyVbs2S3E425ilpf74VGBxIVElVE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PgFIk8L6KXgDSd3ArofYmAHLNJuLvsjJVVcCRjMogJO1IuI8KHXhYgKL5lhlJ/fQn ZuUK0WFXNkSXzpxo+wmavy/xVe8Jf9MqPdmOluNk7RLwF8bu8IYtQfEgGPp+OdE8Nf PVaYp4fkrRFGdXD5i2ZgkmyU4CpMFK6BFJGmhwJe98AB+7NY9vmkfBtlGSifsCcPet EHsSsIPVJM+GksPCF+PUcWk7gCwpnhHZKUm2mj4fw0tVXZpViMT5Q3pAssbNfYTm4p YlQiaFRd73q2Ki7QVv/NZdH4WIu9gmSoVYmvF4ZbcBYpAr2rLoUNpuOj9ggz3vKGto Kzq+POAOCE2OQ== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Wei Chen , Helge Deller , Sasha Levin , javierm@redhat.com, tzimmermann@suse.de, wsa+renesas@sang-engineering.com, linux-fbdev@vger.kernel.org, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 6.1 22/34] fbdev: tgafb: Fix potential divide by zero Date: Wed, 22 Mar 2023 15:59:14 -0400 Message-Id: <20230322195926.1996699-22-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322195926.1996699-1-sashal@kernel.org> References: <20230322195926.1996699-1-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: 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 251dbd282f5ed..84d5daef97666 100644 --- a/drivers/video/fbdev/tgafb.c +++ b/drivers/video/fbdev/tgafb.c @@ -173,6 +173,9 @@ 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