From patchwork Thu Sep 9 13:26:46 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Li Jinlin X-Patchwork-Id: 12483161 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=-16.7 required=3.0 tests=BAYES_00, 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 DB45EC4167E for ; Thu, 9 Sep 2021 13:10:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BDDF861209 for ; Thu, 9 Sep 2021 13:10:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1351040AbhIINLZ (ORCPT ); Thu, 9 Sep 2021 09:11:25 -0400 Received: from szxga01-in.huawei.com ([45.249.212.187]:19020 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1355446AbhIIM6v (ORCPT ); Thu, 9 Sep 2021 08:58:51 -0400 Received: from dggemv703-chm.china.huawei.com (unknown [172.30.72.56]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4H4zTF5YQKzbmDw; Thu, 9 Sep 2021 20:53:37 +0800 (CST) Received: from dggema773-chm.china.huawei.com (10.1.198.217) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.8; Thu, 9 Sep 2021 20:57:39 +0800 Received: from localhost.huawei.com (10.175.124.27) by dggema773-chm.china.huawei.com (10.1.198.217) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2308.8; Thu, 9 Sep 2021 20:57:38 +0800 From: Li Jinlin To: , <^C@kernel.org>, , , CC: , , , , Subject: [PATCH] fix UAF in bfq_io_set_weight_legacy() Date: Thu, 9 Sep 2021 21:26:46 +0800 Message-ID: <20210909132646.1921280-1-lijinlin3@huawei.com> X-Mailer: git-send-email 2.27.0 MIME-Version: 1.0 X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggema773-chm.china.huawei.com (10.1.198.217) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org From: Li Jinlin KASAN reports a use-after-free report when doing fuzz test: [693354.104835] ================================================================== [693354.105094] BUG: KASAN: use-after-free in bfq_io_set_weight_legacy+0xd3/0x160 [693354.105336] Read of size 4 at addr ffff888be0a35664 by task sh/1453338 [693354.105607] CPU: 41 PID: 1453338 Comm: sh Kdump: loaded Not tainted 4.18.0-147 [693354.105610] Hardware name: Huawei 2288H V5/BC11SPSCB0, BIOS 0.81 07/02/2018 [693354.105612] Call Trace: [693354.105621] dump_stack+0xf1/0x19b [693354.105626] ? show_regs_print_info+0x5/0x5 [693354.105634] ? printk+0x9c/0xc3 [693354.105638] ? cpumask_weight+0x1f/0x1f [693354.105648] print_address_description+0x70/0x360 [693354.105654] kasan_report+0x1b2/0x330 [693354.105659] ? bfq_io_set_weight_legacy+0xd3/0x160 [693354.105665] ? bfq_io_set_weight_legacy+0xd3/0x160 [693354.105670] bfq_io_set_weight_legacy+0xd3/0x160 [693354.105675] ? bfq_cpd_init+0x20/0x20 [693354.105683] cgroup_file_write+0x3aa/0x510 [693354.105693] ? ___slab_alloc+0x507/0x540 [693354.105698] ? cgroup_file_poll+0x60/0x60 [693354.105702] ? 0xffffffff89600000 [693354.105708] ? usercopy_abort+0x90/0x90 [693354.105716] ? mutex_lock+0xef/0x180 [693354.105726] kernfs_fop_write+0x1ab/0x280 [693354.105732] ? cgroup_file_poll+0x60/0x60 [693354.105738] vfs_write+0xe7/0x230 [693354.105744] ksys_write+0xb0/0x140 [693354.105749] ? __ia32_sys_read+0x50/0x50 [693354.105760] do_syscall_64+0x112/0x370 [693354.105766] ? syscall_return_slowpath+0x260/0x260 [693354.105772] ? do_page_fault+0x9b/0x270 [693354.105779] ? prepare_exit_to_usermode+0xf9/0x1a0 [693354.105784] ? enter_from_user_mode+0x30/0x30 [693354.105793] entry_SYSCALL_64_after_hwframe+0x65/0xca [693354.105875] Allocated by task 1453337: [693354.106001] kasan_kmalloc+0xa0/0xd0 [693354.106006] kmem_cache_alloc_node_trace+0x108/0x220 [693354.106010] bfq_pd_alloc+0x96/0x120 [693354.106015] blkcg_activate_policy+0x1b7/0x2b0 [693354.106020] bfq_create_group_hierarchy+0x1e/0x80 [693354.106026] bfq_init_queue+0x678/0x8c0 [693354.106031] blk_mq_init_sched+0x1f8/0x460 [693354.106037] elevator_switch_mq+0xe1/0x240 [693354.106041] elevator_switch+0x25/0x40 [693354.106045] elv_iosched_store+0x1a1/0x230 [693354.106049] queue_attr_store+0x78/0xb0 [693354.106053] kernfs_fop_write+0x1ab/0x280 [693354.106056] vfs_write+0xe7/0x230 [693354.106060] ksys_write+0xb0/0x140 [693354.106064] do_syscall_64+0x112/0x370 [693354.106069] entry_SYSCALL_64_after_hwframe+0x65/0xca [693354.106114] Freed by task 1453336: [693354.106225] __kasan_slab_free+0x130/0x180 [693354.106229] kfree+0x90/0x1b0 [693354.106233] blkcg_deactivate_policy+0x12c/0x220 [693354.106238] bfq_exit_queue+0xf5/0x110 [693354.106241] blk_mq_exit_sched+0x104/0x130 [693354.106245] __elevator_exit+0x45/0x60 [693354.106249] elevator_switch_mq+0xd6/0x240 [693354.106253] elevator_switch+0x25/0x40 [693354.106257] elv_iosched_store+0x1a1/0x230 [693354.106261] queue_attr_store+0x78/0xb0 [693354.106264] kernfs_fop_write+0x1ab/0x280 [693354.106268] vfs_write+0xe7/0x230 [693354.106271] ksys_write+0xb0/0x140 [693354.106275] do_syscall_64+0x112/0x370 [693354.106280] entry_SYSCALL_64_after_hwframe+0x65/0xca [693354.106329] The buggy address belongs to the object at ffff888be0a35580 which belongs to the cache kmalloc-1k of size 1024 [693354.106736] The buggy address is located 228 bytes inside of 1024-byte region [ffff888be0a35580, ffff888be0a35980) [693354.107114] The buggy address belongs to the page: [693354.107273] page:ffffea002f828c00 count:1 mapcount:0 mapping:ffff888107c17080 index:0x0 compound_mapcount: 0 [693354.107606] flags: 0x17ffffc0008100(slab|head) [693354.107760] raw: 0017ffffc0008100 ffffea002fcbc808 ffffea0030bd3a08 ffff888107c17080 [693354.108020] raw: 0000000000000000 00000000001c001c 00000001ffffffff 0000000000000000 [693354.108278] page dumped because: kasan: bad access detected [693354.108511] Memory state around the buggy address: [693354.108671] ffff888be0a35500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [693354.116396] ffff888be0a35580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [693354.124473] >ffff888be0a35600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [693354.132421] ^ [693354.140284] ffff888be0a35680: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [693354.147912] ffff888be0a35700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [693354.155281] ================================================================== Freeing bfqg is protected by queue lock in blkcg_deactivate_policy(), but getting/using bfqg is protected by blkcg lock in bfq_io_set_weight_legacy(). If bfq_io_set_weight_legacy() get bfqg before freeing bfqg and use bfqg in the after, the use-after-free will occur. CPU0 CPU1 blkcg_deactivate_policy spin_lock_irq(&q->queue_lock) bfq_io_set_weight_legacy spin_lock_irq(&blkcg->lock) blkg_to_bfqg(blkg) pd_to_bfqg(blkg->pd[pol->plid]) ^^^^^^blkg->pd[pol->plid] != NULL bfqg != NULL pol->pd_free_fn(blkg->pd[pol->plid]) pd_to_bfqg(blkg->pd[pol->plid]) bfqg_put(bfqg) kfree(bfqg) blkg->pd[pol->plid] = NULL spin_unlock_irq(q->queue_lock); bfq_group_set_weight(bfqg, val, 0) bfqg->entity.new_weight ^^^^^^trigger uaf here spin_unlock_irq(&blkcg->lock); To fix this use-after-free, instead of holding blkcg->lock while walking ->blkg_list and getting/using bfqg, RCU walk ->blkg_list and hold the blkg's queue lock while getting/using bfqg. Fixes: e21b7a0b9887 ("block, bfq: add full hierarchical scheduling and cgroups support") Signed-off-by: Li Jinlin --- block/bfq-cgroup.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/block/bfq-cgroup.c b/block/bfq-cgroup.c index e2f14508f2d6..7209060caa90 100644 --- a/block/bfq-cgroup.c +++ b/block/bfq-cgroup.c @@ -1025,21 +1025,25 @@ static int bfq_io_set_weight_legacy(struct cgroup_subsys_state *css, struct blkcg *blkcg = css_to_blkcg(css); struct bfq_group_data *bfqgd = blkcg_to_bfqgd(blkcg); struct blkcg_gq *blkg; + struct bfq_group *bfqg; int ret = -ERANGE; if (val < BFQ_MIN_WEIGHT || val > BFQ_MAX_WEIGHT) return ret; ret = 0; - spin_lock_irq(&blkcg->lock); bfqgd->weight = (unsigned short)val; - hlist_for_each_entry(blkg, &blkcg->blkg_list, blkcg_node) { - struct bfq_group *bfqg = blkg_to_bfqg(blkg); + + rcu_read_lock(); + hlist_for_each_entry_rcu(blkg, &blkcg->blkg_list, blkcg_node) { + spin_lock_irq(&blkg->q->queue_lock); + bfqg = blkg_to_bfqg(blkg); if (bfqg) bfq_group_set_weight(bfqg, val, 0); + spin_unlock_irq(&blkg->q->queue_lock); } - spin_unlock_irq(&blkcg->lock); + rcu_read_unlock(); return ret; }