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 1243DC7619A for ; Wed, 22 Mar 2023 20:13:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231701AbjCVUN1 (ORCPT ); Wed, 22 Mar 2023 16:13:27 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232091AbjCVUMy (ORCPT ); Wed, 22 Mar 2023 16:12:54 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3491D7FD79; Wed, 22 Mar 2023 13:04:36 -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 0FCF6622B4; Wed, 22 Mar 2023 20:03:52 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 88309C4339B; Wed, 22 Mar 2023 20:03:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1679515431; bh=0vnA3WU9n71Hksc/Fk2ECnvm3tBZSD5qLPZsrYMfSA0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gCrIJVT48kvbjhFtY6QmfpivzuEbFevCFdThJVCBKwgvezjnMJJqiX98XanBU3M20 NwiWikW9Ucm44SZ7FhrZTaa4mjMZ8vB58rOSrmWqWq4vjFNmFtCHF9SUg8efrrLLWQ llgG+HeIhnbbLJzVrRfWxdRdRjL+MlnTWQMcOE6o1trubCptDFEsjAWZo2LkNlvkmH zqi9mSYieOC+G7YI/qoiwIEM1gs6DNe1izqL7M5x5EWOmFFtfs+1VMM7ubOB4565Z/ ITOcyx2uWgXL2TZ3QytOE8cH0/ps4loZ8ux8TzT8upsDkcgqo4q0VzZPo9YsMcM4yh 7Je/dTkdJYlPw== 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 4.14 4/9] fbdev: tgafb: Fix potential divide by zero Date: Wed, 22 Mar 2023 16:03:31 -0400 Message-Id: <20230322200337.1997810-4-sashal@kernel.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230322200337.1997810-1-sashal@kernel.org> References: <20230322200337.1997810-1-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-kernel@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 65ba9921506e2..9d2912947eef6 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