From nobody Thu Apr 2 16:38:12 2026 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 8FB59ECAAD8 for ; Fri, 23 Sep 2022 13:35:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232004AbiIWNfa (ORCPT ); Fri, 23 Sep 2022 09:35:30 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45576 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231300AbiIWNfR (ORCPT ); Fri, 23 Sep 2022 09:35:17 -0400 Received: from szxga08-in.huawei.com (szxga08-in.huawei.com [45.249.212.255]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D2D3A91D07; Fri, 23 Sep 2022 06:35:15 -0700 (PDT) Received: from dggemv704-chm.china.huawei.com (unknown [172.30.72.53]) by szxga08-in.huawei.com (SkyGuard) with ESMTP id 4MYtMX2znzz1P6vc; Fri, 23 Sep 2022 21:31:04 +0800 (CST) Received: from kwepemm600013.china.huawei.com (7.193.23.68) by dggemv704-chm.china.huawei.com (10.3.19.47) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 23 Sep 2022 21:35:13 +0800 Received: from huawei.com (10.175.127.227) by kwepemm600013.china.huawei.com (7.193.23.68) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.31; Fri, 23 Sep 2022 21:35:13 +0800 From: Zhihao Cheng To: , , CC: , , , , Subject: [PATCH v3 1/3] quota: Check next/prev free block number after reading from quota file Date: Fri, 23 Sep 2022 21:45:52 +0800 Message-ID: <20220923134555.2623931-2-chengzhihao1@huawei.com> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20220923134555.2623931-1-chengzhihao1@huawei.com> References: <20220923134555.2623931-1-chengzhihao1@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.175.127.227] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600013.china.huawei.com (7.193.23.68) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Following process: Init: v2_read_file_info: <3> dqi_free_blk 0 dqi_free_entry 5 dqi_blks 6 Step 1. chown bin f_a -> dquot_acquire -> v2_write_dquot: qtree_write_dquot do_insert_tree find_free_dqentry get_free_dqblk write_blk(info->dqi_blocks) // info->dqi_blocks =3D 6, failure. The content in physical block (corresponding to blk 6) is random. Step 2. chown root f_a -> dquot_transfer -> dqput_all -> dqput -> ext4_release_dquot -> v2_release_dquot -> qtree_delete_dquot: dquot_release remove_tree free_dqentry put_free_dqblk(6) info->dqi_free_blk =3D blk // info->dqi_free_blk =3D 6 Step 3. drop cache (buffer head for block 6 is released) Step 4. chown bin f_b -> dquot_acquire -> commit_dqblk -> v2_write_dquot: qtree_write_dquot do_insert_tree find_free_dqentry get_free_dqblk dh =3D (struct qt_disk_dqdbheader *)buf blk =3D info->dqi_free_blk // 6 ret =3D read_blk(info, blk, buf) // The content of buf is random info->dqi_free_blk =3D le32_to_cpu(dh->dqdh_next_free) // random blk Step 5. chown bin f_c -> notify_change -> ext4_setattr -> dquot_transfer: dquot =3D dqget -> acquire_dquot -> ext4_acquire_dquot -> dquot_acquire -> commit_dqblk -> v2_write_dquot -> dq_insert_tree: do_insert_tree find_free_dqentry get_free_dqblk blk =3D info->dqi_free_blk // If blk < 0 and blk is not an error code, it will be returned as dquot transfer_to[USRQUOTA] =3D dquot // A random negative value __dquot_transfer(transfer_to) dquot_add_inodes(transfer_to[cnt]) spin_lock(&dquot->dq_dqb_lock) // page fault , which will lead to kernel page fault: Quota error (device sda): qtree_write_dquot: Error -8000 occurred while creating quota BUG: unable to handle page fault for address: ffffffffffffe120 #PF: supervisor write access in kernel mode #PF: error_code(0x0002) - not-present page Oops: 0002 [#1] PREEMPT SMP CPU: 0 PID: 5974 Comm: chown Not tainted 6.0.0-rc1-00004 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) RIP: 0010:_raw_spin_lock+0x3a/0x90 Call Trace: dquot_add_inodes+0x28/0x270 __dquot_transfer+0x377/0x840 dquot_transfer+0xde/0x540 ext4_setattr+0x405/0x14d0 notify_change+0x68e/0x9f0 chown_common+0x300/0x430 __x64_sys_fchownat+0x29/0x40 In order to avoid accessing invalid quota memory address, this patch adds block number checking of next/prev free block read from quota file. Fetch a reproducer in [Link]. Link: https://bugzilla.kernel.org/show_bug.cgi?id=3D216372 Fixes: 1da177e4c3f4152 ("Linux-2.6.12-rc2") CC: stable@vger.kernel.org Signed-off-by: Zhihao Cheng --- fs/quota/quota_tree.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c index 5f2405994280..7e65d67de9f3 100644 --- a/fs/quota/quota_tree.c +++ b/fs/quota/quota_tree.c @@ -71,6 +71,35 @@ static ssize_t write_blk(struct qtree_mem_dqinfo *info, = uint blk, char *buf) return ret; } =20 +static inline int do_check_range(struct super_block *sb, const char *val_n= ame, + uint val, uint min_val, uint max_val) +{ + if (val < min_val || val > max_val) { + quota_error(sb, "Getting %s %u out of range %u-%u", + val_name, val, min_val, max_val); + return -EUCLEAN; + } + + return 0; +} + +static int check_dquot_block_header(struct qtree_mem_dqinfo *info, + struct qt_disk_dqdbheader *dh) +{ + int err =3D 0; + + err =3D do_check_range(info->dqi_sb, "dqdh_next_free", + le32_to_cpu(dh->dqdh_next_free), 0, + info->dqi_blocks - 1); + if (err) + return err; + err =3D do_check_range(info->dqi_sb, "dqdh_prev_free", + le32_to_cpu(dh->dqdh_prev_free), 0, + info->dqi_blocks - 1); + + return err; +} + /* Remove empty block from list and return it */ static int get_free_dqblk(struct qtree_mem_dqinfo *info) { @@ -85,6 +114,9 @@ static int get_free_dqblk(struct qtree_mem_dqinfo *info) ret =3D read_blk(info, blk, buf); if (ret < 0) goto out_buf; + ret =3D check_dquot_block_header(info, dh); + if (ret) + goto out_buf; info->dqi_free_blk =3D le32_to_cpu(dh->dqdh_next_free); } else { @@ -232,6 +264,9 @@ static uint find_free_dqentry(struct qtree_mem_dqinfo *= info, *err =3D read_blk(info, blk, buf); if (*err < 0) goto out_buf; + *err =3D check_dquot_block_header(info, dh); + if (*err) + goto out_buf; } else { blk =3D get_free_dqblk(info); if ((int)blk < 0) { @@ -424,6 +459,9 @@ static int free_dqentry(struct qtree_mem_dqinfo *info, = struct dquot *dquot, goto out_buf; } dh =3D (struct qt_disk_dqdbheader *)buf; + ret =3D check_dquot_block_header(info, dh); + if (ret) + goto out_buf; le16_add_cpu(&dh->dqdh_entries, -1); if (!le16_to_cpu(dh->dqdh_entries)) { /* Block got free? */ ret =3D remove_free_dqentry(info, buf, blk); --=20 2.31.1