syzbot

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BUG: KASAN: slab-use-after-free in instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
BUG: KASAN: slab-use-after-free in atomic_long_inc_return include/linux/atomic/atomic-instrumented.h:3609 [inline]
BUG: KASAN: slab-use-after-free in bch2_dev_get fs/bcachefs/sb-members.h:114 [inline]
BUG: KASAN: slab-use-after-free in bch2_get_next_dev+0x371/0x4c0 fs/bcachefs/sb-members.h:145
Write of size 8 at addr ffff88806078c040 by task kworker/u9:4/5996

CPU: 0 UID: 0 PID: 5996 Comm: kworker/u9:4 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Workqueue: bcachefs_journal journal_write_done
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x2b0/0x2c0 mm/kasan/generic.c:200
 instrument_atomic_read_write include/linux/instrumented.h:96 [inline]
 atomic_long_inc_return include/linux/atomic/atomic-instrumented.h:3609 [inline]
 bch2_dev_get fs/bcachefs/sb-members.h:114 [inline]
 bch2_get_next_dev+0x371/0x4c0 fs/bcachefs/sb-members.h:145
 bch2_do_discards+0x20/0x160 fs/bcachefs/alloc_background.c:1984
 journal_write_done+0x119a/0x13d0 fs/bcachefs/journal_io.c:1821
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>

Allocated by task 10103:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 poison_kmalloc_redzone mm/kasan/common.c:397 [inline]
 __kasan_kmalloc+0x93/0xb0 mm/kasan/common.c:414
 kasan_kmalloc include/linux/kasan.h:260 [inline]
 __kmalloc_cache_noprof+0x3d5/0x6f0 mm/slub.c:5397
 kmalloc_noprof include/linux/slab.h:956 [inline]
 kzalloc_noprof include/linux/slab.h:1090 [inline]
 __bch2_dev_alloc+0xa7/0xc30 fs/bcachefs/super.c:1487
 bch2_dev_alloc+0xcd/0x180 fs/bcachefs/super.c:1558
 bch2_fs_alloc fs/bcachefs/super.c:1051 [inline]
 bch2_fs_open+0x2477/0x2600 fs/bcachefs/super.c:2433
 bch2_fs_get_tree+0x44f/0x1520 fs/bcachefs/fs.c:2472
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1751
 fc_mount fs/namespace.c:1274 [inline]
 do_new_mount_fc fs/namespace.c:3726 [inline]
 do_new_mount+0x302/0xa10 fs/namespace.c:3802
 do_mount fs/namespace.c:4125 [inline]
 __do_sys_mount fs/namespace.c:4324 [inline]
 __se_sys_mount+0x313/0x410 fs/namespace.c:4301
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 10103:
 kasan_save_stack mm/kasan/common.c:56 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:77
 __kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:587
 kasan_save_free_info mm/kasan/kasan.h:406 [inline]
 poison_slab_object mm/kasan/common.c:252 [inline]
 __kasan_slab_free+0x5b/0x80 mm/kasan/common.c:284
 kasan_slab_free include/linux/kasan.h:233 [inline]
 slab_free_hook mm/slub.c:2484 [inline]
 slab_free mm/slub.c:6121 [inline]
 kfree+0x199/0x6d0 mm/slub.c:6329
 kobject_cleanup lib/kobject.c:689 [inline]
 kobject_release lib/kobject.c:720 [inline]
 kref_put include/linux/kref.h:65 [inline]
 kobject_put+0x228/0x480 lib/kobject.c:737
 bch2_fs_free+0x440/0x5a0 fs/bcachefs/super.c:728
 deactivate_locked_super+0xbc/0x130 fs/super.c:473
 cleanup_mnt+0x425/0x4c0 fs/namespace.c:1393
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xec/0x130 kernel/entry/common.c:43
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0xfa0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559
 insert_work+0x3d/0x330 kernel/workqueue.c:2186
 __queue_work+0xcd2/0xfb0 kernel/workqueue.c:2341
 queue_work_on+0x181/0x270 kernel/workqueue.c:2392
 queue_work include/linux/workqueue.h:669 [inline]
 bch2_dev_do_discards fs/bcachefs/alloc_background.c:1974 [inline]
 bch2_do_discards+0xd0/0x160 fs/bcachefs/alloc_background.c:1985
 journal_write_done+0x119a/0x13d0 fs/bcachefs/journal_io.c:1821
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Second to last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:56
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:559
 insert_work+0x3d/0x330 kernel/workqueue.c:2186
 __queue_work+0xcd2/0xfb0 kernel/workqueue.c:2341
 queue_work_on+0x181/0x270 kernel/workqueue.c:2392
 queue_work include/linux/workqueue.h:669 [inline]
 bch2_dev_do_discards fs/bcachefs/alloc_background.c:1974 [inline]
 bch2_do_discards+0xd0/0x160 fs/bcachefs/alloc_background.c:1985
 journal_write_done+0x119a/0x13d0 fs/bcachefs/journal_io.c:1821
 process_one_work kernel/workqueue.c:3263 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3346
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3427
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x47c/0x820 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

The buggy address belongs to the object at ffff88806078c000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 64 bytes inside of
 freed 4096-byte region [ffff88806078c000, ffff88806078d000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x60788
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000040(head|node=0|zone=1|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 00fff00000000040 ffff88801a842140 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a842140 dead000000000122 0000000000000000
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea000181e201 00000000ffffffff 00000000ffffffff
head: ffffffffffffffff 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 10103, tgid 10102 (syz.2.346), ts 355433894601, free_ts 355402269853
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3863
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5153
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 alloc_slab_page mm/slub.c:2996 [inline]
 allocate_slab+0x8a/0x330 mm/slub.c:3164
 new_slab mm/slub.c:3218 [inline]
 ___slab_alloc+0xbd1/0x13f0 mm/slub.c:4420
 __slab_alloc+0x55/0xa0 mm/slub.c:4511
 __slab_alloc_node mm/slub.c:4586 [inline]
 slab_alloc_node mm/slub.c:4996 [inline]
 __do_kmalloc_node mm/slub.c:5365 [inline]
 __kmalloc_noprof+0x471/0x7f0 mm/slub.c:5378
 mempool_init_node+0x1ea/0x4d0 mm/mempool.c:221
 mempool_init_noprof+0x3a/0x50 mm/mempool.c:250
 bch2_fs_btree_interior_update_init+0xc3/0x120 fs/bcachefs/btree_update_interior.c:2849
 bch2_fs_init_rw+0x1b9/0x2d0 fs/bcachefs/super.c:813
 bch2_fs_alloc fs/bcachefs/super.c:1022 [inline]
 bch2_fs_open+0x233d/0x2600 fs/bcachefs/super.c:2433
 bch2_fs_get_tree+0x44f/0x1520 fs/bcachefs/fs.c:2472
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1751
 fc_mount fs/namespace.c:1274 [inline]
 do_new_mount_fc fs/namespace.c:3726 [inline]
 do_new_mount+0x302/0xa10 fs/namespace.c:3802
page last free pid 5910 tgid 5910 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 __free_frozen_pages+0xbc4/0xd30 mm/page_alloc.c:2900
 __slab_free+0x2e7/0x390 mm/slub.c:5596
 qlink_free mm/kasan/quarantine.c:163 [inline]
 qlist_free_all+0x97/0x140 mm/kasan/quarantine.c:179
 kasan_quarantine_reduce+0x148/0x160 mm/kasan/quarantine.c:286
 __kasan_slab_alloc+0x22/0x80 mm/kasan/common.c:349
 kasan_slab_alloc include/linux/kasan.h:250 [inline]
 slab_post_alloc_hook mm/slub.c:4710 [inline]
 slab_alloc_node mm/slub.c:5008 [inline]
 kmem_cache_alloc_noprof+0x367/0x6e0 mm/slub.c:5015
 getname_flags+0xb8/0x540 fs/namei.c:146
 getname include/linux/fs.h:2906 [inline]
 do_sys_openat2+0xbc/0x1c0 fs/open.c:1429
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1461
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88806078bf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88806078bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88806078c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88806078c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88806078c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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