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BUG: KASAN: slab-use-after-free in bch2_get_next_dev+0x371/0x4c0
Write of size 8 at addr ffff888033184040 by task kworker/u12:3/8995

CPU: 1 UID: 0 PID: 8995 Comm: kworker/u12:3 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Workqueue: bcachefs_journal journal_write_done
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 print_report+0xca/0x240
 kasan_report+0x118/0x150
 kasan_check_range+0x2b0/0x2c0
 bch2_get_next_dev+0x371/0x4c0
 bch2_do_discards+0x20/0x160
 journal_write_done+0x119a/0x13d0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 24489:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x3d5/0x6f0
 __bch2_dev_alloc+0xa7/0xc30
 bch2_dev_alloc+0xcd/0x180
 bch2_fs_open+0x2477/0x2600
 bch2_fs_get_tree+0x44f/0x1520
 vfs_get_tree+0x92/0x2b0
 do_new_mount+0x302/0x9e0
 __se_sys_mount+0x313/0x410
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5847:
 kasan_save_track+0x3e/0x80
 __kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5c/0x80
 kfree+0x19a/0x6d0
 kobject_put+0x22b/0x480
 bch2_fs_free+0x440/0x5a0
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x425/0x4c0
 task_work_run+0x1d4/0x260
 exit_to_user_mode_loop+0xe9/0x130
 do_syscall_64+0x2bd/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 insert_work+0x3d/0x330
 __queue_work+0xcd2/0xfb0
 queue_work_on+0x181/0x270
 bch2_do_discards+0xd0/0x160
 journal_write_done+0x119a/0x13d0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30

Second to last potentially related work creation:
 kasan_save_stack+0x3e/0x60
 kasan_record_aux_stack+0xbd/0xd0
 insert_work+0x3d/0x330
 __queue_work+0xcd2/0xfb0
 queue_work_on+0x181/0x270
 bch2_do_discards+0xd0/0x160
 journal_write_done+0x119a/0x13d0
 process_scheduled_works+0xae1/0x17b0
 worker_thread+0x8a0/0xda0
 kthread+0x711/0x8a0
 ret_from_fork+0x4bc/0x870
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff888033184000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 64 bytes inside of
 freed 4096-byte region [ffff888033184000, ffff888033185000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x33180
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 ffff88801ac42140 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801ac42140 dead000000000100 dead000000000122
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000cc6001 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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5852, tgid 5852 (syz-executor), ts 568059717458, free_ts 555060866870
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x2365/0x2440
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x96/0x3a0
 ___slab_alloc+0xe94/0x1920
 __slab_alloc+0x65/0x100
 __kmalloc_noprof+0x471/0x7f0
 tomoyo_realpath_from_path+0xe3/0x5d0
 tomoyo_path_perm+0x213/0x4b0
 security_inode_getattr+0x12f/0x330
 vfs_statx+0x18e/0x550
 vfs_fstatat+0x118/0x170
 __x64_sys_newfstatat+0x116/0x190
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5830 tgid 5830 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 __put_partials+0x146/0x170
 put_cpu_partial+0x1f2/0x2e0
 __slab_free+0x2b9/0x390
 qlist_free_all+0x97/0x140
 kasan_quarantine_reduce+0x148/0x160
 __kasan_slab_alloc+0x22/0x80
 kmem_cache_alloc_noprof+0x367/0x6e0
 jbd2__journal_start+0x146/0x5b0
 __ext4_journal_start_sb+0x227/0x5c0
 ext4_dirty_inode+0x93/0x110
 __mark_inode_dirty+0x2ec/0xe10
 file_update_time+0x40c/0x490
 ext4_page_mkwrite+0x20e/0x1190
 do_page_mkwrite+0x14d/0x310
 do_wp_page+0x268d/0x5800

Memory state around the buggy address:
 ffff888033183f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888033183f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888033184000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff888033184080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888033184100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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