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 5D678C76196 for ; Mon, 3 Apr 2023 14:31:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233475AbjDCObX (ORCPT ); Mon, 3 Apr 2023 10:31:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34660 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233477AbjDCObX (ORCPT ); Mon, 3 Apr 2023 10:31:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4146A35003 for ; Mon, 3 Apr 2023 07:31:22 -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 CC15A61E04 for ; Mon, 3 Apr 2023 14:31:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DD54AC433EF; Mon, 3 Apr 2023 14:31:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680532281; bh=lB0ovEWypQQayEnK8c96qt+2LqdTYexrTsR2RunHWgQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=x5vaGaTKVhXiW8mVrDWfE54R+3GX8uOs9auZZX4oYRttA9evadu5GKhZfrJdyjA79 Z4DTrLL8kcYZ1fezEhP20wQsx+vvdw19M2tKzFTtyekGzO+E/nHKOMfLWGtsKRa1/P dQPZHZb3+1whOwfyMU7TlZsGwJZOzAY9hqzYKi9s= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Wei Chen , Helge Deller , Sasha Levin Subject: [PATCH 5.15 15/99] fbdev: tgafb: Fix potential divide by zero Date: Mon, 3 Apr 2023 16:08:38 +0200 Message-Id: <20230403140358.648761963@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230403140356.079638751@linuxfoundation.org> References: <20230403140356.079638751@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@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 ae0cf55406369..b9b00a1ffe222 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