mode=40755
    flags=(15300000)
    journal_seq=4
    hash_seed=ece93825deac2443
    hash_type=siphash
    bi_size=0
    bi_sectors=0
    bi_version=0
    bi_atime=2770562249
    bi_ctime=2780562352
    bi_mtime=2780562352
    bi_otime=2770562249
    bi_uid=0
    bi_gid=0
    bi_nlink=0
    bi_generation=0
    bi_dev=0
    bi_data_checksum=0
    bi_compression=0
    bi_project=0
    bi_background_compression=0
    bi_data_replicas=0
    bi_promote_target=0
    bi_foreground_target=0
    bi_background_target=0
    bi_erasure_code=0
    bi_fields_set=0
    bi_dir=4096
    bi_dir_offset=189491840996961599
    bi_subvol=0
    bi_parent_subvol=0
    bi_nocow=0
    bi_depth=0
    bi_inodes_32bit=0
    bi_casefold=0, fixing
 done
bcachefs (loop0): check_extents...
bcachefs (loop0): key in missing inode, found keys:
  u64s 7 type extent 4099:8:U32_MAX len 8 ver 0: durability: 1 crc: c_size 8 size 8 offset 0 nonce 0 csum none 0:0  compress incompressible ptr: 0:60:0 gen 0
  , fixing
bcachefs (loop0): key in missing inode, found keys:
  u64s 10 type inline_data 4100:8:U32_MAX len 8 ver 0: datalen 40: 2f746d702f73797a2d696d61676567656e3931343136303536352f66696c6530
  , fixing
bcachefs (loop0): key in missing inode, found keys:
  u64s 7 type inline_data 536870912:8:U32_MAX len 8 ver 0: datalen 16: 73797a6b616c6c657273000000000000
  , fixing
bcachefs (loop0): key in missing inode, found keys:
  u64s 7 type extent 536870913:24:U32_MAX len 24 ver 0: durability: 1 crc: c_size 8 size 24 offset 0 nonce 0 csum none 0:0  compress lz4 ptr: 0:60:8 gen 0
  , fixing
==================================================================
BUG: KASAN: use-after-free in __extent_entry_type fs/bcachefs/extents.h:53 [inline]
BUG: KASAN: use-after-free in extent_entry_is_crc fs/bcachefs/extents.h:120 [inline]
BUG: KASAN: use-after-free in check_extent_overbig+0x273/0x7b0 fs/bcachefs/fsck.c:1848
Read of size 8 at addr ffff888055b42050 by task syz.0.0/5356

CPU: 0 UID: 0 PID: 5356 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
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
 __extent_entry_type fs/bcachefs/extents.h:53 [inline]
 extent_entry_is_crc fs/bcachefs/extents.h:120 [inline]
 check_extent_overbig+0x273/0x7b0 fs/bcachefs/fsck.c:1848
 bch2_check_extents+0x56b/0x3d20 fs/bcachefs/fsck.c:1982
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x3bd/0x1060 fs/bcachefs/recovery_passes.c:539
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:610
 bch2_fs_recovery+0x2690/0x3a50 fs/bcachefs/recovery.c:1016
 bch2_fs_start+0xaaf/0xda0 fs/bcachefs/super.c:1213
 bch2_fs_get_tree+0xb39/0x1520 fs/bcachefs/fs.c:2488
 vfs_get_tree+0x92/0x2b0 fs/super.c:1815
 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808
 do_mount fs/namespace.c:4136 [inline]
 __do_sys_mount fs/namespace.c:4347 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4324
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fd47ff9038a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fd480d9be68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fd480d9bef0 RCX: 00007fd47ff9038a
RDX: 0000200000000040 RSI: 0000200000000200 RDI: 00007fd480d9beb0
RBP: 0000200000000040 R08: 00007fd480d9bef0 R09: 0000000001000800
R10: 0000000001000800 R11: 0000000000000246 R12: 0000200000000200
R13: 00007fd480d9beb0 R14: 0000000000005a20 R15: 0000200000000080
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x55b42
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 0000000000000000 ffffea000156d090 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 5, migratetype Unmovable, gfp_mask 0x42800(GFP_NOWAIT|__GFP_COMP), pid 49, tgid 49 (kworker/0:1H), ts 77698070706, free_ts 79783262892
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2416
 ___kmalloc_large_node+0x5f/0x1b0 mm/slub.c:4306
 __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:4337
 __do_kmalloc_node mm/slub.c:4353 [inline]
 __kvmalloc_node_noprof+0x6d/0x5f0 mm/slub.c:5052
 btree_bounce_alloc fs/bcachefs/btree_io.c:127 [inline]
 bch2_btree_node_read_done+0x32f6/0x5550 fs/bcachefs/btree_io.c:1278
 btree_node_read_work+0x40e/0xe60 fs/bcachefs/btree_io.c:1440
 process_one_work kernel/workqueue.c:3236 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x3fc/0x770 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
page last free pid 5356 tgid 5355 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_pages_ok+0xa83/0xbe0 mm/page_alloc.c:1571
 free_large_kmalloc+0x13a/0x1f0 mm/slub.c:4805
 btree_bounce_free fs/bcachefs/btree_io.c:115 [inline]
 btree_node_sort+0x117f/0x1760 fs/bcachefs/btree_io.c:383
 bch2_btree_post_write_cleanup+0x11f/0xad0 fs/bcachefs/btree_io.c:2607
 bch2_btree_node_prep_for_write+0x337/0x650 fs/bcachefs/btree_trans_commit.c:95
 bch2_trans_lock_write+0x669/0xba0 fs/bcachefs/btree_trans_commit.c:131
 do_bch2_trans_commit fs/bcachefs/btree_trans_commit.c:850 [inline]
 __bch2_trans_commit+0x2773/0x8870 fs/bcachefs/btree_trans_commit.c:1085
 bch2_trans_commit fs/bcachefs/btree_update.h:241 [inline]
 check_extent fs/bcachefs/fsck.c:1938 [inline]
 bch2_check_extents+0x2a72/0x3d20 fs/bcachefs/fsck.c:1982
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x3bd/0x1060 fs/bcachefs/recovery_passes.c:539
 bch2_run_recovery_passes+0x184/0x210 fs/bcachefs/recovery_passes.c:610
 bch2_fs_recovery+0x2690/0x3a50 fs/bcachefs/recovery.c:1016
 bch2_fs_start+0xaaf/0xda0 fs/bcachefs/super.c:1213
 bch2_fs_get_tree+0xb39/0x1520 fs/bcachefs/fs.c:2488
 vfs_get_tree+0x92/0x2b0 fs/super.c:1815
 do_new_mount+0x2a2/0x9e0 fs/namespace.c:3808
 do_mount fs/namespace.c:4136 [inline]
 __do_sys_mount fs/namespace.c:4347 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4324

Memory state around the buggy address:
 ffff888055b41f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888055b41f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888055b42000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                 ^
 ffff888055b42080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888055b42100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================