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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,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 EDB57C15508 for ; Fri, 5 Mar 2021 12:43:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C89486501F for ; Fri, 5 Mar 2021 12:43:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232956AbhCEMnN (ORCPT ); Fri, 5 Mar 2021 07:43:13 -0500 Received: from mail.kernel.org ([198.145.29.99]:59066 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233847AbhCEMm2 (ORCPT ); Fri, 5 Mar 2021 07:42:28 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 60C016501C; Fri, 5 Mar 2021 12:42:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1614948147; bh=Mqw/Xi4CtknF9CnDt+xfZR2WJq/GQJJN7ERbesdt2Zo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ZXCqQHN0OXVcNE9gnDUPRDG/b/dDYCgRTG7JU5xV1gb7PvM1mPfouGFP67nTjtwpf fap4W+vaxvhs/EVvQA8bo1BchHH4L6L29xhGVb4E4QDjQRRq5Dvkcd2ZoNNHbc1HFT ELUSOZzVOeYWTMjknfalkqkKTmnECBLMwexSR06w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, syzbot+36315852ece4132ec193@syzkaller.appspotmail.com, Randy Dunlap , Dave Kleikamp , jfs-discussion@lists.sourceforge.net, kernel test robot Subject: [PATCH 4.9 18/41] JFS: more checks for invalid superblock Date: Fri, 5 Mar 2021 13:22:25 +0100 Message-Id: <20210305120852.182320874@linuxfoundation.org> X-Mailer: git-send-email 2.30.1 In-Reply-To: <20210305120851.255002428@linuxfoundation.org> References: <20210305120851.255002428@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Randy Dunlap commit 3bef198f1b17d1bb89260bad947ef084c0a2d1a6 upstream. syzbot is feeding invalid superblock data to JFS for mount testing. JFS does not check several of the fields -- just assumes that they are good since the JFS_MAGIC and version fields are good. In this case (syzbot reproducer), we have s_l2bsize == 0xda0c, pad == 0xf045, and s_state == 0x50, all of which are invalid IMO. Having s_l2bsize == 0xda0c causes this UBSAN warning: UBSAN: shift-out-of-bounds in fs/jfs/jfs_mount.c:373:25 shift exponent -9716 is negative s_l2bsize can be tested for correctness. pad can be tested for non-0 and punted. s_state can be tested for its valid values and punted. Do those 3 tests and if any of them fails, report the superblock as invalid/corrupt and let fsck handle it. With this patch, chkSuper() says this when JFS_DEBUG is enabled: jfs_mount: Mount Failure: superblock is corrupt! Mount JFS Failure: -22 jfs_mount failed w/return code = -22 The obvious problem with this method is that next week there could be another syzbot test that uses different fields for invalid values, this making this like a game of whack-a-mole. syzkaller link: https://syzkaller.appspot.com/bug?extid=36315852ece4132ec193 Reported-by: syzbot+36315852ece4132ec193@syzkaller.appspotmail.com Reported-by: kernel test robot # v2 Signed-off-by: Randy Dunlap Signed-off-by: Dave Kleikamp Cc: jfs-discussion@lists.sourceforge.net Signed-off-by: Greg Kroah-Hartman --- fs/jfs/jfs_filsys.h | 1 + fs/jfs/jfs_mount.c | 10 ++++++++++ 2 files changed, 11 insertions(+) --- a/fs/jfs/jfs_filsys.h +++ b/fs/jfs/jfs_filsys.h @@ -281,5 +281,6 @@ * fsck() must be run to repair */ #define FM_EXTENDFS 0x00000008 /* file system extendfs() in progress */ +#define FM_STATE_MAX 0x0000000f /* max value of s_state */ #endif /* _H_JFS_FILSYS */ --- a/fs/jfs/jfs_mount.c +++ b/fs/jfs/jfs_mount.c @@ -49,6 +49,7 @@ #include #include +#include #include "jfs_incore.h" #include "jfs_filsys.h" @@ -378,6 +379,15 @@ static int chkSuper(struct super_block * sbi->bsize = bsize; sbi->l2bsize = le16_to_cpu(j_sb->s_l2bsize); + /* check some fields for possible corruption */ + if (sbi->l2bsize != ilog2((u32)bsize) || + j_sb->pad != 0 || + le32_to_cpu(j_sb->s_state) > FM_STATE_MAX) { + rc = -EINVAL; + jfs_err("jfs_mount: Mount Failure: superblock is corrupt!"); + goto out; + } + /* * For now, ignore s_pbsize, l2bfactor. All I/O going through buffer * cache.