, fixing
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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:1847
Read of size 8 at addr ffff88806bd02050 by task syz-executor167/5827

CPU: 1 UID: 0 PID: 5827 Comm: syz-executor167 Not tainted 6.16.0-rc4-syzkaller-00013-g66701750d556 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 __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:1847
 bch2_check_extents+0x5b0/0x4520 fs/bcachefs/fsck.c:2002
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x395/0x1010 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:1005
 bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1212
 bch2_fs_get_tree+0xafc/0x14f0 fs/bcachefs/fs.c:2490
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902
 do_mount fs/namespace.c:4239 [inline]
 __do_sys_mount fs/namespace.c:4450 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4427
 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: 0033:0x7f4673b5851a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 5e 04 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffc34e64088 EFLAGS: 00000282 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc34e640a0 RCX: 00007f4673b5851a
RDX: 0000200000000000 RSI: 0000200000000200 RDI: 00007ffc34e640a0
RBP: 0000200000000200 R08: 00007ffc34e640e0 R09: 00000000000059cd
R10: 00000000028000c9 R11: 0000000000000282 R12: 0000200000000000
R13: 0000000000000004 R14: 0000000000000003 R15: 00007ffc34e640e0
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6bd02
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 ffffea0001af4090 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 25, tgid 25 (kworker/1:0H), ts 77587477268, free_ts 84496733498
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1704
 prep_new_page mm/page_alloc.c:1712 [inline]
 get_page_from_freelist+0x21d5/0x22b0 mm/page_alloc.c:3669
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:4959
 __alloc_pages_noprof+0xa/0x30 mm/page_alloc.c:4993
 __alloc_pages_node_noprof include/linux/gfp.h:284 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:311 [inline]
 ___kmalloc_large_node+0x85/0x210 mm/slub.c:4272
 __kmalloc_large_node_noprof+0x18/0x90 mm/slub.c:4300
 __do_kmalloc_node mm/slub.c:4316 [inline]
 __kvmalloc_node_noprof+0x6d/0x5f0 mm/slub.c:5015
 btree_bounce_alloc fs/bcachefs/btree_io.c:127 [inline]
 bch2_btree_node_read_done+0x33c4/0x5700 fs/bcachefs/btree_io.c:1280
 btree_node_read_work+0x426/0xe30 fs/bcachefs/btree_io.c:1415
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xae1/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
 kthread+0x711/0x8a0 kernel/kthread.c:464
 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 5827 tgid 5827 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1248 [inline]
 __free_pages_ok+0xa3b/0xc10 mm/page_alloc.c:1424
 __folio_put+0x21b/0x2c0 mm/swap.c:112
 folio_put include/linux/mm.h:1356 [inline]
 free_large_kmalloc+0x145/0x200 mm/slub.c:4768
 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:2582
 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:1958 [inline]
 bch2_check_extents+0x2b24/0x4520 fs/bcachefs/fsck.c:2002
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x395/0x1010 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:1005
 bch2_fs_start+0xa99/0xd90 fs/bcachefs/super.c:1212
 bch2_fs_get_tree+0xafc/0x14f0 fs/bcachefs/fs.c:2490
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902

Memory state around the buggy address:
 ffff88806bd01f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806bd01f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806bd02000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                                                 ^
 ffff88806bd02080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806bd02100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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