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 AA4F5C76196 for ; Mon, 3 Apr 2023 14:22:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233155AbjDCOWt (ORCPT ); Mon, 3 Apr 2023 10:22:49 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46844 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233142AbjDCOWs (ORCPT ); Mon, 3 Apr 2023 10:22:48 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E50222D7D7 for ; Mon, 3 Apr 2023 07:22:26 -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 8147261C32 for ; Mon, 3 Apr 2023 14:22:26 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9950EC433EF; Mon, 3 Apr 2023 14:22:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680531746; bh=6rJG97ZzxVmIyk1bTkmXt1OfZk0tUqXxGyQT7Wn+4hM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=gut5TerPVKMK14EY9vbI0WHSzkBVMiDtjcmaeUp9xdDnRZ2nas0KyXIK9AR493aSF QPzo3uO7jmiNgHHVWah7da8PfHagrrsxLWmEsMQXzy8L3a03hpPgNueTVVc8K60J1B wuy0SGJ+QvCUqC4fExPr7St65Ot9/EYfD9M7g0A4= 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 5.4 065/104] fbdev: tgafb: Fix potential divide by zero Date: Mon, 3 Apr 2023 16:08:57 +0200 Message-Id: <20230403140406.776209095@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230403140403.549815164@linuxfoundation.org> References: <20230403140403.549815164@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 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