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 5FF02C32750 for ; Fri, 2 Aug 2019 09:45:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 366492086A for ; Fri, 2 Aug 2019 09:45:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739123; bh=viojl1Wh9riP/rQAtRHoMpxVkEnfhYOshj1b+skoEmE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=INpIcesEEkAwsisCllJq0nX4T5s20EPJjcbcfPF8sLwqT6GokVUmFgpV3ZnjqeJwF oCtafgIzHYgolNAQWup0jHgJrStgHjZ/4Dx/1Iev9jw6lfYKS2wcYuGaKH6ecxC+vr llGV35ZkYdiyG4AHWf1ksNOwEQQyzcpyp67XjOuY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2405426AbfHBJpW (ORCPT ); Fri, 2 Aug 2019 05:45:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:48988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2403831AbfHBJpR (ORCPT ); Fri, 2 Aug 2019 05:45:17 -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 D144221726; Fri, 2 Aug 2019 09:45:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564739116; bh=viojl1Wh9riP/rQAtRHoMpxVkEnfhYOshj1b+skoEmE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=0vauINYqPeGCvejJReZtDNi9M1pKNgDIQP0ur5XhR3vCCSsNgO5D7tiWsnMspc+BK 6686xCyOTLYGq7s/Hh6C7XOuZl2EKd8zI+YeUhBcNJEOD+sVtWlEmM7LvTTP6Sd1S3 MXL4c5M97qsZTgq2pFlfqFfJUfMy1zQBwG+nLxAM= 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 4.9 105/223] floppy: fix out-of-bounds read in next_valid_format Date: Fri, 2 Aug 2019 11:35:30 +0200 Message-Id: <20190802092246.036345213@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 5635f897ed83fd539df78e98ba69ee91592f9bb8 ] This fixes a global out-of-bounds read access in the next_valid_format function of the floppy driver. The values from autodetect field of the struct floppy_drive_params are used as indices for the floppy_type array in the next_valid_format function 'floppy_type[DP->autodetect[probed_format]].sect'. To trigger the bug, one could use a value out of range and set the drive parameters with the FDSETDRVPRM ioctl. A floppy disk is not required to be inserted. CAP_SYS_ADMIN is required to call FDSETDRVPRM. The patch adds the check for values of the autodetect field to be in the '0 <= x < ARRAY_SIZE(floppy_type)' range of the floppy_type array indices. 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 | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) --- a/drivers/block/floppy.c +++ b/drivers/block/floppy.c @@ -3384,6 +3384,20 @@ static int fd_getgeo(struct block_device return 0; } +static bool valid_floppy_drive_params(const short autodetect[8]) +{ + size_t floppy_type_size = ARRAY_SIZE(floppy_type); + size_t i = 0; + + for (i = 0; i < 8; ++i) { + if (autodetect[i] < 0 || + autodetect[i] >= floppy_type_size) + return false; + } + + return true; +} + static int fd_locked_ioctl(struct block_device *bdev, fmode_t mode, unsigned int cmd, unsigned long param) { @@ -3510,6 +3524,8 @@ static int fd_locked_ioctl(struct block_ SUPBOUND(size, strlen((const char *)outparam) + 1); break; case FDSETDRVPRM: + if (!valid_floppy_drive_params(inparam.dp.autodetect)) + return -EINVAL; *UDP = inparam.dp; break; case FDGETDRVPRM: @@ -3707,6 +3723,8 @@ static int compat_setdrvprm(int drive, return -EPERM; if (copy_from_user(&v, arg, sizeof(struct compat_floppy_drive_params))) return -EFAULT; + if (!valid_floppy_drive_params(v.autodetect)) + return -EINVAL; mutex_lock(&floppy_mutex); UDP->cmos = v.cmos; UDP->max_dtr = v.max_dtr;