| Message ID | c339c5643ceba67771b559ffae0fb4c169426cef.1699014305.git.fdmanana@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | btrfs: fix race between accounting qgroup extents and removing a qgroup | expand |
On Fri, Nov 03, 2023 at 12:26:25PM +0000, fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > 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: > <TASK> > __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 > </TASK> > > 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 <fdmanana@suse.com> Reviewed-by: Josef Bacik <josef@toxicpanda.com> Thanks, Josef
On 2023/11/3 22:56, fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > 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: > <TASK> > __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 > </TASK> > > 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 <fdmanana@suse.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Thanks, Qu > --- > 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;
On Fri, Nov 03, 2023 at 12:26:25PM +0000, fdmanana@kernel.org wrote: > From: Filipe Manana <fdmanana@suse.com> > > 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: > <TASK> > __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 > </TASK> > > 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 <fdmanana@suse.com> Added to misc-next, thanks.
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;