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=unavailable 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 4E002C32750 for ; Fri, 2 Aug 2019 09:33:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 247832184B for ; Fri, 2 Aug 2019 09:33:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564738415; bh=PPvA7ml7LFFB5y0n9lNb3gNkDyaZeZkeeFX6exxKxJ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=vAXsa1gPAWzuwlh6MDn1lYfW+gX6mUNBk0LbP1CTIb83tbOgQ7SLyYKOtcf45IVYZ SQC+/c2hMqDhWw5oq2jcg8i8WDajSH8LM9iR4BU7nNRAZOdKS3+ngaX1g2BcdAo3PE M/0XXT1iLyFGl4MjF7AWjemoLtSFXFSm+pR6lTLg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391411AbfHBJdd (ORCPT ); Fri, 2 Aug 2019 05:33:33 -0400 Received: from mail.kernel.org ([198.145.29.99]:32846 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390413AbfHBJd2 (ORCPT ); Fri, 2 Aug 2019 05:33:28 -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 8084021855; Fri, 2 Aug 2019 09:33:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564738408; bh=PPvA7ml7LFFB5y0n9lNb3gNkDyaZeZkeeFX6exxKxJ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TJvDz4JPJEuctrNlQt7rd8P9U8p+oPnXYx93x0i5IobNZmlX3L3l+T4KNYjc6Em9L DZON+lexIAw/HzhQwEPA/rBtMwsMh1+bihMBFMTpPHqQqvDl9lLVRypI9M7iHOOzw6 AgtEltAAKZn1TUmWO54SwDot2M8x1VdMCoR8IQ3Q= 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 4.4 075/158] floppy: fix out-of-bounds read in copy_buffer Date: Fri, 2 Aug 2019 11:28:16 +0200 Message-Id: <20190802092219.257002324@linuxfoundation.org> X-Mailer: git-send-email 2.22.0 In-Reply-To: <20190802092203.671944552@linuxfoundation.org> References: <20190802092203.671944552@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) ||