From patchwork Fri Nov 3 12:26:25 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Filipe Manana X-Patchwork-Id: 13444503 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 1C7E3C4332F for ; Fri, 3 Nov 2023 12:26:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346858AbjKCM0e (ORCPT ); Fri, 3 Nov 2023 08:26:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54776 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1346700AbjKCM0d (ORCPT ); Fri, 3 Nov 2023 08:26:33 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2790B191 for ; Fri, 3 Nov 2023 05:26:30 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3676EC433C8 for ; Fri, 3 Nov 2023 12:26:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1699014389; bh=dzE4bKY0pbUyGgOHm9sRsGOVv/yCOq1egatm2e5ZD+Q=; h=From:To:Subject:Date:From; b=nIn7UcRC+iacRC74rxfGSctj0pXNH1Z2RQ1y8Kdt/T4BtmWf5GToEmY0ztACE1Zf6 Bz4f64CTRWdgzrqqDjDGfFXcnU2xwK9lgRxHD3yJw6wkt8k9AEkgzNawWo0Q6qVVPN fZn+18Dx6NWwJLyvfzVj6rzPDPHLTIt224QtOVOMeBIvMJUSxZ2A7FxqjXM25szPwp zOB1ivqYiaCTOFIOZQXsCgBfADiaAi4ln3UKFjIT0LBnX7fiKZGTVDNaDJ6QFcBzVq jOmu9Tlkg/g+ROYYYGhN8snywCnviJjo0f1M8IMUvOVtwZHKWFWoVG954j1gtiNGPq 4t44NbT2qCb7w== From: fdmanana@kernel.org To: linux-btrfs@vger.kernel.org Subject: [PATCH] btrfs: fix race between accounting qgroup extents and removing a qgroup Date: Fri, 3 Nov 2023 12:26:25 +0000 Message-Id: X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org From: Filipe Manana When doing qgroup accounting for an extent, we take the spinlock fs_info->qgroup_lock and then add qgroups to the local list (iterator) named "qgroups". These qgroups are found in the fs_info->qgroup_tree rbtree. After we're done, we unlock fs_info->qgroup_lock and then call qgroup_iterator_nested_clean(), which will iterate over all the qgroups added to the local list "qgroups" and then delete them from the list. Deleting a qgroup from the list can however result in a use-after-free if a qgroup remove operation happens after we unlock fs_info->qgroup_lock and before or while we are at qgroup_iterator_nested_clean(). Fix this by calling qgroup_iterator_nested_clean() while still holding the lock fs_info->qgroup_lock - we don't need it under the 'out' label since before taking the lock the "qgroups" list is always empty. This guarantees safety because btrfs_remove_qgroup() takes that lock before removing a qgroup from the rbtree fs_info->qgroup_tree. This was reported by syzbot with the following stack traces: BUG: KASAN: slab-use-after-free in __list_del_entry_valid_or_report+0x2f/0x130 lib/list_debug.c:49 Read of size 8 at addr ffff888027e420b0 by task kworker/u4:3/48 CPU: 1 PID: 48 Comm: kworker/u4:3 Not tainted 6.6.0-syzkaller-10396-g4652b8e4f3ff #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/09/2023 Workqueue: btrfs-qgroup-rescan btrfs_work_helper Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:364 [inline] print_report+0x163/0x540 mm/kasan/report.c:475 kasan_report+0x175/0x1b0 mm/kasan/report.c:588 __list_del_entry_valid_or_report+0x2f/0x130 lib/list_debug.c:49 __list_del_entry_valid include/linux/list.h:124 [inline] __list_del_entry include/linux/list.h:215 [inline] list_del_init include/linux/list.h:287 [inline] qgroup_iterator_nested_clean fs/btrfs/qgroup.c:2623 [inline] btrfs_qgroup_account_extent+0x18b/0x1150 fs/btrfs/qgroup.c:2883 qgroup_rescan_leaf fs/btrfs/qgroup.c:3543 [inline] btrfs_qgroup_rescan_worker+0x1078/0x1c60 fs/btrfs/qgroup.c:3604 btrfs_work_helper+0x37c/0xbd0 fs/btrfs/async-thread.c:315 process_one_work kernel/workqueue.c:2630 [inline] process_scheduled_works+0x90f/0x1400 kernel/workqueue.c:2703 worker_thread+0xa5f/0xff0 kernel/workqueue.c:2784 kthread+0x2d3/0x370 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 Allocated by task 6355: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4f/0x70 mm/kasan/common.c:52 ____kasan_kmalloc mm/kasan/common.c:374 [inline] __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383 kmalloc include/linux/slab.h:600 [inline] kzalloc include/linux/slab.h:721 [inline] btrfs_quota_enable+0xee9/0x2060 fs/btrfs/qgroup.c:1209 btrfs_ioctl_quota_ctl+0x143/0x190 fs/btrfs/ioctl.c:3705 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Freed by task 6355: kasan_save_stack mm/kasan/common.c:45 [inline] kasan_set_track+0x4f/0x70 mm/kasan/common.c:52 kasan_save_free_info+0x28/0x40 mm/kasan/generic.c:522 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236 kasan_slab_free include/linux/kasan.h:164 [inline] slab_free_hook mm/slub.c:1800 [inline] slab_free_freelist_hook mm/slub.c:1826 [inline] slab_free mm/slub.c:3809 [inline] __kmem_cache_free+0x263/0x3a0 mm/slub.c:3822 btrfs_remove_qgroup+0x764/0x8c0 fs/btrfs/qgroup.c:1787 btrfs_ioctl_qgroup_create+0x185/0x1e0 fs/btrfs/ioctl.c:3811 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:871 [inline] __se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Last potentially related work creation: kasan_save_stack+0x3f/0x60 mm/kasan/common.c:45 __kasan_record_aux_stack+0xad/0xc0 mm/kasan/generic.c:492 __call_rcu_common kernel/rcu/tree.c:2667 [inline] call_rcu+0x167/0xa70 kernel/rcu/tree.c:2781 kthread_worker_fn+0x4ba/0xa90 kernel/kthread.c:823 kthread+0x2d3/0x370 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 Second to last potentially related work creation: kasan_save_stack+0x3f/0x60 mm/kasan/common.c:45 __kasan_record_aux_stack+0xad/0xc0 mm/kasan/generic.c:492 __call_rcu_common kernel/rcu/tree.c:2667 [inline] call_rcu+0x167/0xa70 kernel/rcu/tree.c:2781 kthread_worker_fn+0x4ba/0xa90 kernel/kthread.c:823 kthread+0x2d3/0x370 kernel/kthread.c:388 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242 The buggy address belongs to the object at ffff888027e42000 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 176 bytes inside of freed 512-byte region [ffff888027e42000, ffff888027e42200) The buggy address belongs to the physical page: page:ffffea00009f9000 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x27e40 head:ffffea00009f9000 order:2 entire_mapcount:0 nr_pages_mapped:0 pincount:0 flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 00fff00000000840 ffff888012c41c80 ffffea0000a5ba00 dead000000000002 raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected page_owner tracks the page as allocated page last allocated via order 2, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4514, tgid 4514 (udevadm), ts 24598439480, free_ts 23755696267 set_page_owner include/linux/page_owner.h:31 [inline] post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1536 prep_new_page mm/page_alloc.c:1543 [inline] get_page_from_freelist+0x31db/0x3360 mm/page_alloc.c:3170 __alloc_pages+0x255/0x670 mm/page_alloc.c:4426 alloc_slab_page+0x6a/0x160 mm/slub.c:1870 allocate_slab mm/slub.c:2017 [inline] new_slab+0x84/0x2f0 mm/slub.c:2070 ___slab_alloc+0xc85/0x1310 mm/slub.c:3223 __slab_alloc mm/slub.c:3322 [inline] __slab_alloc_node mm/slub.c:3375 [inline] slab_alloc_node mm/slub.c:3468 [inline] __kmem_cache_alloc_node+0x19d/0x270 mm/slub.c:3517 kmalloc_trace+0x2a/0xe0 mm/slab_common.c:1098 kmalloc include/linux/slab.h:600 [inline] kzalloc include/linux/slab.h:721 [inline] kernfs_fop_open+0x3e7/0xcc0 fs/kernfs/file.c:670 do_dentry_open+0x8fd/0x1590 fs/open.c:948 do_open fs/namei.c:3622 [inline] path_openat+0x2845/0x3280 fs/namei.c:3779 do_filp_open+0x234/0x490 fs/namei.c:3809 do_sys_openat2+0x13e/0x1d0 fs/open.c:1440 do_sys_open fs/open.c:1455 [inline] __do_sys_openat fs/open.c:1471 [inline] __se_sys_openat fs/open.c:1466 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1466 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b page last free stack trace: reset_page_owner include/linux/page_owner.h:24 [inline] free_pages_prepare mm/page_alloc.c:1136 [inline] free_unref_page_prepare+0x8c3/0x9f0 mm/page_alloc.c:2312 free_unref_page+0x37/0x3f0 mm/page_alloc.c:2405 discard_slab mm/slub.c:2116 [inline] __unfreeze_partials+0x1dc/0x220 mm/slub.c:2655 put_cpu_partial+0x17b/0x250 mm/slub.c:2731 __slab_free+0x2b6/0x390 mm/slub.c:3679 qlink_free mm/kasan/quarantine.c:166 [inline] qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:185 kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:292 __kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305 kasan_slab_alloc include/linux/kasan.h:188 [inline] slab_post_alloc_hook+0x67/0x3d0 mm/slab.h:762 slab_alloc_node mm/slub.c:3478 [inline] slab_alloc mm/slub.c:3486 [inline] __kmem_cache_alloc_lru mm/slub.c:3493 [inline] kmem_cache_alloc+0x104/0x2c0 mm/slub.c:3502 getname_flags+0xbc/0x4f0 fs/namei.c:140 do_sys_openat2+0xd2/0x1d0 fs/open.c:1434 do_sys_open fs/open.c:1455 [inline] __do_sys_openat fs/open.c:1471 [inline] __se_sys_openat fs/open.c:1466 [inline] __x64_sys_openat+0x247/0x290 fs/open.c:1466 do_syscall_x64 arch/x86/entry/common.c:51 [inline] do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82 entry_SYSCALL_64_after_hwframe+0x63/0x6b Memory state around the buggy address: ffff888027e41f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888027e42000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff888027e42080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888027e42100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff888027e42180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb Fixes: dce28769a33a ("btrfs: qgroup: use qgroup_iterator_nested to in qgroup_update_refcnt()") Reported-by: syzbot+e0b615318f8fcfc01ceb@syzkaller.appspotmail.com Link: https://lore.kernel.org/linux-btrfs/00000000000091a5b2060936bf6d@google.com/ Signed-off-by: Filipe Manana Reviewed-by: Josef Bacik Reviewed-by: Qu Wenruo --- fs/btrfs/qgroup.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index edb84cc03237..e48eba7e9379 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -2874,13 +2874,19 @@ int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr, qgroup_update_counters(fs_info, &qgroups, nr_old_roots, nr_new_roots, num_bytes, seq); + /* + * We're done using the iterator, release all its qgroups while holding + * fs_info->qgroup_lock so that we don't race with btrfs_remove_qgroup() + * and trigger use-after-free accesses to qgroups. + */ + qgroup_iterator_nested_clean(&qgroups); + /* * Bump qgroup_seq to avoid seq overlap */ fs_info->qgroup_seq += max(nr_old_roots, nr_new_roots) + 1; spin_unlock(&fs_info->qgroup_lock); out_free: - qgroup_iterator_nested_clean(&qgroups); ulist_free(old_roots); ulist_free(new_roots); return ret;