From patchwork Fri Jun 19 14:31:10 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 223793 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 BB2BDC433E2 for ; Fri, 19 Jun 2020 16:24:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9639921707 for ; Fri, 19 Jun 2020 16:24:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592583864; bh=SrQIZo4/w6tvt/sn10MdGljp2fb7x+ziSKjuxf924D4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=p0YY3uv1Oi2SKFR6ldHG5XvXgRN3CAb6bCXseP46LK0G2Y/XEtP3xrqw02tB3Ep6T NpFYFTvxgCEmVJn+MTJieSwkq/k7Qo7e91rfaDhiULGRf+/jmzTyUcoP5kcrrGoFAy HfpTtqOibI1Fx8iUQdZ9KfvMHZ+Nh8oLsGh5zuog= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2394671AbgFSQYU (ORCPT ); Fri, 19 Jun 2020 12:24:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:54252 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390389AbgFSO60 (ORCPT ); Fri, 19 Jun 2020 10:58:26 -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 242BC21919; Fri, 19 Jun 2020 14:58:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592578706; bh=SrQIZo4/w6tvt/sn10MdGljp2fb7x+ziSKjuxf924D4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=XMSh2ajAIng1b2yRRwkEI0uiqWiaYbTUqgSo2ywAw8Y4mvJjAJAXcL/nZW+347e7z 7Qy1MlsYRHFKWZ7e0tK9qNJ9eqgG4WyBGGK8YE5PFh9mkeqtLnPc+iIu5I3oJ/YnVi pRyp1wEUI4K6Fu4j37lXdSWUIeVjXhoJWPTL9j3w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+6f1624f937d9d6911e2d@syzkaller.appspotmail.com, OGAWA Hirofumi , Andrew Morton , Marco Elver , Dmitry Vyukov , Linus Torvalds Subject: [PATCH 4.19 085/267] fat: dont allow to mount if the FAT length == 0 Date: Fri, 19 Jun 2020 16:31:10 +0200 Message-Id: <20200619141652.962191910@linuxfoundation.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20200619141648.840376470@linuxfoundation.org> References: <20200619141648.840376470@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: OGAWA Hirofumi commit b1b65750b8db67834482f758fc385bfa7560d228 upstream. If FAT length == 0, the image doesn't have any data. And it can be the cause of overlapping the root dir and FAT entries. Also Windows treats it as invalid format. Reported-by: syzbot+6f1624f937d9d6911e2d@syzkaller.appspotmail.com Signed-off-by: OGAWA Hirofumi Signed-off-by: Andrew Morton Cc: Marco Elver Cc: Dmitry Vyukov Link: http://lkml.kernel.org/r/87r1wz8mrd.fsf@mail.parknet.co.jp Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- fs/fat/inode.c | 6 ++++++ 1 file changed, 6 insertions(+) --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1519,6 +1519,12 @@ static int fat_read_bpb(struct super_blo goto out; } + if (bpb->fat_fat_length == 0 && bpb->fat32_length == 0) { + if (!silent) + fat_msg(sb, KERN_ERR, "bogus number of FAT sectors"); + goto out; + } + error = 0; out: