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 X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 24FB0C433FF for ; Fri, 2 Aug 2019 09:44:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F16DF2171F for ; Fri, 2 Aug 2019 09:44:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739093; bh=PPvA7ml7LFFB5y0n9lNb3gNkDyaZeZkeeFX6exxKxJ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=2dH6ZD2PoaUtSZ58aQ3yTFVRaXQE+M/48EAmE3qwXh6eJOzJLyyhdXK4J6xAepB5H qGZUoEVvRjSEltCJOyL2xM57XIB9+Z9bInauwqZRsUqlHvrL1AqwxMWNZY39BBOPK6 FbpMuxH+nbxp8CI6k4GjQllR4nYovq/kKZulmmnw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732502AbfHBJov (ORCPT ); Fri, 2 Aug 2019 05:44:51 -0400 Received: from mail.kernel.org ([198.145.29.99]:48220 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2405284AbfHBJoq (ORCPT ); Fri, 2 Aug 2019 05:44:46 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 19B882087E; Fri, 2 Aug 2019 09:44:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739085; bh=PPvA7ml7LFFB5y0n9lNb3gNkDyaZeZkeeFX6exxKxJ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=v/n8VTMjavPiKCFGxhCkSYxZIE6Hnka+FWhiDQ85C/YoOb/FwYGNfGJk0PZwdtT0L F9cROyC4VR+QHKP8L+TKkcPZIDzXG1A/0UeiLD5k3WKuPRvTnKXI1WLM3P0LLIT2Gq faygjnRNFzf6rTQfrGw70pEDdBnJfzyG4vw3uxBw= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Denis Efremov , Willy Tarreau , Linus Torvalds , Sasha Levin Subject: [PATCH 4.9 107/223] floppy: fix out-of-bounds read in copy_buffer Date: Fri, 2 Aug 2019 11:35:32 +0200 Message-Id: <20190802092246.181182014@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190802092238.692035242@linuxfoundation.org> References: <20190802092238.692035242@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org [ Upstream commit da99466ac243f15fbba65bd261bfc75ffa1532b6 ] This fixes a global out-of-bounds read access in the copy_buffer function of the floppy driver. The FDDEFPRM ioctl allows one to set the geometry of a disk. The sect and head fields (unsigned int) of the floppy_drive structure are used to compute the max_sector (int) in the make_raw_rw_request function. It is possible to overflow the max_sector. Next, max_sector is passed to the copy_buffer function and used in one of the memcpy calls. An unprivileged user could trigger the bug if the device is accessible, but requires a floppy disk to be inserted. The patch adds the check for the .sect * .head multiplication for not overflowing in the set_geometry function. The bug was found by syzkaller. Signed-off-by: Denis Efremov Tested-by: Willy Tarreau Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/block/floppy.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3237,8 +3237,10 @@ static int set_geometry(unsigned int cmd int cnt; /* sanity checking for parameters. */ - if (g->sect <= 0 || - g->head <= 0 || + if ((int)g->sect <= 0 || + (int)g->head <= 0 || + /* check for overflow in max_sector */ + (int)(g->sect * g->head) <= 0 || /* check for zero in F_SECT_PER_TRACK */ (unsigned char)((g->sect << 2) >> FD_SIZECODE(g)) == 0 || g->track <= 0 || g->track > UDP->tracks >> STRETCH(g) ||