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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,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 4F4D8C433E0 for ; Thu, 18 Jun 2020 01:26:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2441A2088E for ; Thu, 18 Jun 2020 01:26:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592443588; bh=8rEuU+HOd7oL+2eFUd+0ScN7CiMpOIKu5iY4f3aIeb8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=OaK+/Ib+57B//Ejtv6n7hZNHyvtPyZoJ1ZfH1apNcmbC91ekVWsh8N9pjKvTADwE0 5H4LEy0MaHXTPRxiHE6ZHMt4LQ6nokq5aU2kzH/ElfcvD8aL1IH7qNp/SjSkJkAVGo 0JbvaVYjhdBN9Qg/pc/ahqlnDmVOyWT424Qum98M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730091AbgFRB0Z (ORCPT ); Wed, 17 Jun 2020 21:26:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:56746 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729544AbgFRBXP (ORCPT ); Wed, 17 Jun 2020 21:23:15 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DC86E20776; Thu, 18 Jun 2020 01:23:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592443394; bh=8rEuU+HOd7oL+2eFUd+0ScN7CiMpOIKu5iY4f3aIeb8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vHC1G7fSTeXcdd4UZTuqoWHvdehDYxOmLD94izq/z52NvB/26vLrv+vHhnjJh2waj sm3NDzPOEAqg4ixQRKCFujAtlfiGgGiXk3sZqOaVuuYlsjyBTf+7Dh/DZ9YHvtlfQW a4lBXYWc1ui3xaiZNb2DSW5VkORyjhmrB+2Mf/y8= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: OGAWA Hirofumi , syzbot+6f1624f937d9d6911e2d@syzkaller.appspotmail.com, Andrew Morton , Marco Elver , Dmitry Vyukov , Linus Torvalds , Sasha Levin Subject: [PATCH AUTOSEL 4.19 041/172] fat: don't allow to mount if the FAT length == 0 Date: Wed, 17 Jun 2020 21:20:07 -0400 Message-Id: <20200618012218.607130-41-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200618012218.607130-1-sashal@kernel.org> References: <20200618012218.607130-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: OGAWA Hirofumi [ Upstream commit b1b65750b8db67834482f758fc385bfa7560d228 ] 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: Sasha Levin --- fs/fat/inode.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/fs/fat/inode.c b/fs/fat/inode.c index 70d37a5fd72c..607e1d124062 100644 --- a/fs/fat/inode.c +++ b/fs/fat/inode.c @@ -1519,6 +1519,12 @@ static int fat_read_bpb(struct super_block *sb, struct fat_boot_sector *b, 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: -- 2.25.1