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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8EC17C433F5 for ; Thu, 26 May 2022 07:19:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236623AbiEZHS7 (ORCPT ); Thu, 26 May 2022 03:18:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35724 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233900AbiEZHS5 (ORCPT ); Thu, 26 May 2022 03:18:57 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4905B5AA72 for ; Thu, 26 May 2022 00:18:55 -0700 (PDT) Received: from canpemm500005.china.huawei.com (unknown [172.30.72.56]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4L7zlj2Jlgz1JC8n; Thu, 26 May 2022 15:17:21 +0800 (CST) Received: from huawei.com (10.175.127.227) by canpemm500005.china.huawei.com (7.192.104.229) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.24; Thu, 26 May 2022 15:18:52 +0800 From: Zhang Yi To: CC: , , , , , , Subject: [PATCH] ext4: add reserved GDT blocks check Date: Thu, 26 May 2022 15:32:22 +0800 Message-ID: <20220526073222.380259-1-yi.zhang@huawei.com> X-Mailer: git-send-email 2.31.1 MIME-Version: 1.0 Content-Transfer-Encoding: 7BIT Content-Type: text/plain; charset=US-ASCII X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems706-chm.china.huawei.com (10.3.19.183) To canpemm500005.china.huawei.com (7.192.104.229) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org We capture a NULL pointer issue when resizing a corrupt ext4 image which is freshly clear resize_inode feature (not run e2fsck). It could be simply reproduced by following steps. The problem is because of the resize_inode feature was cleared, and it will convert the filesystem to meta_bg mode in ext4_resize_fs(), but the es->s_reserved_gdt_blocks was not reduced to zero, so could we mistakenly call reserve_backup_gdb() and passing an uninitialized resize_inode to it when adding new group descriptors. mkfs.ext4 /dev/sda 3G tune2fs -O ^resize_inode /dev/sda #forget to run requested e2fsck mount /dev/sda /mnt resize2fs /dev/sda 8G ======== BUG: kernel NULL pointer dereference, address: 0000000000000028 CPU: 19 PID: 3243 Comm: resize2fs Not tainted 5.18.0-rc7-00001-gfde086c5ebfd #748 ... RIP: 0010:ext4_flex_group_add+0xe08/0x2570 ... Call Trace: ext4_resize_fs+0xbec/0x1660 __ext4_ioctl+0x1749/0x24e0 ext4_ioctl+0x12/0x20 __x64_sys_ioctl+0xa6/0x110 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f2dd739617b ======== The fix is simple, add a check in ext4_resize_fs() to make sure that the es->s_reserved_gdt_blocks is zero when the resize_inode feature is disabled. Signed-off-by: Zhang Yi --- fs/ext4/resize.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c index 90a941d20dff..5791eb7c0761 100644 --- a/fs/ext4/resize.c +++ b/fs/ext4/resize.c @@ -2031,6 +2031,9 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count) ext4_warning(sb, "Error opening resize inode"); return PTR_ERR(resize_inode); } + } else if (es->s_reserved_gdt_blocks) { + ext4_error(sb, "resize_inode disabled but reserved GDT blocks non-zero"); + return -EFSCORRUPTED; } if ((!resize_inode && !meta_bg) || n_blocks_count == o_blocks_count) { -- 2.31.1