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BUG: KASAN: slab-use-after-free in bch2_get_next_dev+0x371/0x4c0
Write of size 8 at addr ffff88803fcec040 by task kworker/u12:5/12155

CPU: 0 UID: 0 PID: 12155 Comm: kworker/u12:5 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+0x3fc/0x770
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 12137:
 kasan_save_track+0x3e/0x80
 __kasan_kmalloc+0x93/0xb0
 __kmalloc_cache_noprof+0x230/0x3d0
 __bch2_dev_alloc+0xa7/0xc30
 bch2_dev_alloc+0xcd/0x180
 bch2_fs_open+0x2472/0x2600
 bch2_fs_get_tree+0x44f/0x1520
 vfs_get_tree+0x92/0x2b0
 do_new_mount+0x2a2/0x9e0
 __se_sys_mount+0x317/0x410
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 12150:
 kasan_save_track+0x3e/0x80
 kasan_save_free_info+0x46/0x50
 __kasan_slab_free+0x5b/0x80
 kfree+0x18e/0x440
 kobject_put+0x22b/0x480
 bch2_fs_free+0x440/0x5a0
 deactivate_locked_super+0xbc/0x130
 cleanup_mnt+0x425/0x4c0
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 irqentry_exit_to_user_mode+0x81/0x120
 exc_page_fault+0x9f/0xf0
 asm_exc_page_fault+0x26/0x30

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_discard_one_bucket_fast+0xe1/0x160
 bch2_trigger_alloc+0x24b1/0x4090
 run_one_mem_trigger+0x572/0x710
 __bch2_trans_commit+0x3f60/0x8870
 bch2_inode_delete_keys+0x525/0x700
 bch2_inode_rm+0x282/0x820
 bch2_evict_inode+0x220/0x520
 evict+0x504/0x9c0
 __dentry_kill+0x209/0x660
 dput+0x19f/0x2b0
 __fput+0x68e/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 irqentry_exit_to_user_mode+0x81/0x120
 exc_page_fault+0x9f/0xf0
 asm_exc_page_fault+0x26/0x30

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_discard_one_bucket_fast+0xe1/0x160
 bch2_trigger_alloc+0x24b1/0x4090
 run_one_mem_trigger+0x572/0x710
 __bch2_trans_commit+0x3f60/0x8870
 bch2_inode_delete_keys+0x525/0x700
 bch2_inode_rm+0x282/0x820
 bch2_evict_inode+0x220/0x520
 evict+0x504/0x9c0
 __dentry_kill+0x209/0x660
 dput+0x19f/0x2b0
 __fput+0x68e/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 get_signal+0x1286/0x1340
 arch_do_signal_or_restart+0x9a/0x750
 irqentry_exit_to_user_mode+0x81/0x120
 exc_page_fault+0x9f/0xf0
 asm_exc_page_fault+0x26/0x30

The buggy address belongs to the object at ffff88803fcec000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 64 bytes inside of
 freed 4096-byte region [ffff88803fcec000, ffff88803fced000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3fce8
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 ffff88801a442140 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000040 ffff88801a442140 dead000000000100 dead000000000122
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 00fff00000000003 ffffea0000ff3a01 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 9534, tgid 9519 (syz.3.847), ts 227509736759, free_ts 225063312505
 post_alloc_hook+0x240/0x2a0
 get_page_from_freelist+0x21e4/0x22c0
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 allocate_slab+0x8a/0x370
 ___slab_alloc+0xbeb/0x1410
 __kmalloc_noprof+0x305/0x4f0
 tomoyo_realpath_from_path+0xe3/0x5d0
 tomoyo_path_number_perm+0x1e8/0x5a0
 security_file_ioctl+0xcb/0x2d0
 __se_sys_ioctl+0x47/0x170
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 9462 tgid 9462 stack trace:
 __free_frozen_pages+0xbc4/0xd30
 vfree+0x25a/0x400
 snd_pcm_lib_free_pages+0x250/0x2e0
 snd_pcm_release_substream+0x2b7/0x480
 snd_pcm_oss_release+0x144/0x250
 __fput+0x44c/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x6b5/0x2300
 do_group_exit+0x21c/0x2d0
 __x64_sys_exit_group+0x3f/0x40
 x64_sys_call+0x21f7/0x2200
 do_syscall_64+0xfa/0x3b0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88803fcebf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88803fcebf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88803fcec000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88803fcec080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88803fcec100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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