u64s 7 type dirent 4096:7012347908543992434:U32_MAX len 0 ver 0: file1 -> 1073741824 type reg, fixing
bcachefs (loop0): dirent points to missing inode:
  u64s 8 type dirent 4096:8117119959317756843:U32_MAX len 0 ver 0: file.cold -> 1073741826 type reg, fixing
==================================================================
BUG: KASAN: use-after-free in check_dirent fs/bcachefs/fsck.c:2395 [inline]
BUG: KASAN: use-after-free in bch2_check_dirents+0x1fac/0x33f0 fs/bcachefs/fsck.c:2421
Read of size 1 at addr ffff88804c960190 by task syz.0.72/6493

CPU: 1 UID: 0 PID: 6493 Comm: syz.0.72 Not tainted 6.16.0-rc7-syzkaller #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:378 [inline]
 print_report+0xca/0x230 mm/kasan/report.c:480
 kasan_report+0x118/0x150 mm/kasan/report.c:593
 check_dirent fs/bcachefs/fsck.c:2395 [inline]
 bch2_check_dirents+0x1fac/0x33f0 fs/bcachefs/fsck.c:2421
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x392/0x1010 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: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: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: 0033:0x7fe2ed59014a
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:00007fe2ee339e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fe2ee339ef0 RCX: 00007fe2ed59014a
RDX: 000020000000f640 RSI: 000020000000f680 RDI: 00007fe2ee339eb0
RBP: 000020000000f640 R08: 00007fe2ee339ef0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000020000000f680
R13: 00007fe2ee339eb0 R14: 000000000000f633 R15: 0000200000000000
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4c960
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0001329808 ffff88813fffc6a8 0000000000000000
raw: 0000000000000000 0000000000000005 00000000f0000000 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 5, migratetype Reclaimable, gfp_mask 0x442810(GFP_NOWAIT|__GFP_RECLAIMABLE|__GFP_COMP|__GFP_ACCOUNT), pid 152, tgid 152 (kworker/u8:5), ts 129727530692, free_ts 135168579663
 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_node_data_alloc+0xdc/0x270 fs/bcachefs/btree_cache.c:151
 bch2_btree_node_mem_alloc+0x618/0x1820 fs/bcachefs/btree_cache.c:836
 __bch2_btree_node_alloc fs/bcachefs/btree_update_interior.c:302 [inline]
 bch2_btree_reserve_get+0x2f3/0x1810 fs/bcachefs/btree_update_interior.c:534
 bch2_btree_update_start+0x18ff/0x1de0 fs/bcachefs/btree_update_interior.c:1289
 bch2_btree_node_rewrite+0x17e/0x1120 fs/bcachefs/btree_update_interior.c:2246
 bch2_btree_node_rewrite_key+0x273/0x320 fs/bcachefs/btree_update_interior.c:2312
 async_btree_node_rewrite_work+0x110/0x4f0 fs/bcachefs/btree_update_interior.c:2369
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xade/0x17b0 kernel/workqueue.c:3321
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3402
page last free pid 6493 tgid 6492 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: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_dirent fs/bcachefs/fsck.c:2390 [inline]
 bch2_check_dirents+0x1c5c/0x33f0 fs/bcachefs/fsck.c:2421
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x392/0x1010 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: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:1804
 do_new_mount+0x24a/0xa40 fs/namespace.c:3902

Memory state around the buggy address:
 ffff88804c960080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804c960100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88804c960180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                         ^
 ffff88804c960200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804c960280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================