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BUG: KASAN: slab-use-after-free in bch2_get_next_dev+0x371/0x4c0
Write of size 8 at addr ffff88810fd8c040 by task kworker/u12:1/8225

CPU: 0 UID: 0 PID: 8225 Comm: kworker/u12:1 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+0x439/0x7d0
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Allocated by task 16022:
 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 16022:
 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
 bch2_fs_get_tree+0xb6e/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

The buggy address belongs to the object at ffff88810fd8c000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 64 bytes inside of
 freed 4096-byte region [ffff88810fd8c000, ffff88810fd8d000)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x10fd88
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0x57ff00000000040(head|node=1|zone=2|lastcpupid=0x7ff)
page_type: f5(slab)
raw: 057ff00000000040 ffff88801a442140 dead000000000100 dead000000000122
raw: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 057ff00000000040 ffff88801a442140 dead000000000100 dead000000000122
head: 0000000000000000 0000000000040004 00000000f5000000 0000000000000000
head: 057ff00000000003 ffffea00043f6201 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 5298, tgid 5298 (S10udev), ts 23283936090, free_ts 0
 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/0x1420
 __kmalloc_noprof+0x305/0x4f0
 tomoyo_realpath_from_path+0xe3/0x5d0
 tomoyo_init_log+0x10b0/0x1f70
 tomoyo_supervisor+0x340/0x1480
 tomoyo_find_next_domain+0x488/0x1aa0
 tomoyo_bprm_check_security+0x11c/0x180
 security_bprm_check+0x89/0x270
 bprm_execve+0x8ee/0x1450
 do_execveat_common+0x510/0x6a0
 __x64_sys_execve+0x94/0xb0
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88810fd8bf00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88810fd8bf80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88810fd8c000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                           ^
 ffff88810fd8c080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88810fd8c100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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