u64s 7 type dirent 4096:5697049586231069887:U32_MAX len 0 ver 0: file2 -> 536870913 type reg, fixing
bcachefs (loop0): dirent points to missing inode:
  u64s 7 type dirent 4096:7339578760937650561:U32_MAX len 0 ver 0: file3 -> 536870913 type reg, fixing
==================================================================
BUG: KASAN: use-after-free in check_dirent fs/bcachefs/fsck.c:2418 [inline]
BUG: KASAN: use-after-free in bch2_check_dirents+0x1fac/0x33f0 fs/bcachefs/fsck.c:2444
Read of size 1 at addr ffff888047a60110 by task syz.0.99/6548

CPU: 1 UID: 0 PID: 6548 Comm: syz.0.99 Not tainted 6.16.0-rc3-next-20250627-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:408 [inline]
 print_report+0xd2/0x2b0 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 check_dirent fs/bcachefs/fsck.c:2418 [inline]
 bch2_check_dirents+0x1fac/0x33f0 fs/bcachefs/fsck.c:2444
 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:1211
 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: 0033:0x7f600ef900ca
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:00007f600fddfe68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f600fddfef0 RCX: 00007f600ef900ca
RDX: 00002000000000c0 RSI: 0000200000000080 RDI: 00007f600fddfeb0
RBP: 00002000000000c0 R08: 00007f600fddfef0 R09: 0000000000818001
R10: 0000000000818001 R11: 0000000000000246 R12: 0000200000000080
R13: 00007f600fddfeb0 R14: 00000000000059ba R15: 0000200000000480
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x47a60
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea00012bb808 ffff88813fffbf08 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 Unmovable, gfp_mask 0x42800(GFP_NOWAIT|__GFP_COMP), pid 6548, tgid 6547 (syz.0.99), ts 116917080958, free_ts 117082297955
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1848
 prep_new_page mm/page_alloc.c:1856 [inline]
 get_page_from_freelist+0x21e4/0x22c0 mm/page_alloc.c:3855
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5145
 alloc_pages_mpol+0x232/0x4a0 mm/mempolicy.c:2419
 ___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]
 btree_node_sort+0x666/0x1760 fs/bcachefs/btree_io.c:326
 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:98
 bch2_trans_lock_write+0x669/0xba0 fs/bcachefs/btree_trans_commit.c:134
 do_bch2_trans_commit fs/bcachefs/btree_trans_commit.c:856 [inline]
 __bch2_trans_commit+0x2776/0x8910 fs/bcachefs/btree_trans_commit.c:1089
 bch2_trans_commit fs/bcachefs/btree_update.h:255 [inline]
 bch2_str_hash_repair_key+0x2a2d/0x3fa0 fs/bcachefs/str_hash.c:294
 __bch2_str_hash_check_key+0xa65/0xd40 fs/bcachefs/str_hash.c:395
 bch2_str_hash_check_key fs/bcachefs/str_hash.h:429 [inline]
 check_dirent fs/bcachefs/fsck.c:2309 [inline]
 bch2_check_dirents+0x2166/0x33f0 fs/bcachefs/fsck.c:2444
 bch2_run_recovery_pass fs/bcachefs/recovery_passes.c:484 [inline]
 __bch2_run_recovery_passes+0x395/0x1010 fs/bcachefs/recovery_passes.c:539
page last free pid 6548 tgid 6547 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1392 [inline]
 __free_pages_ok+0xa44/0xc20 mm/page_alloc.c:1568
 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:2582
 bch2_btree_node_prep_for_write+0x337/0x650 fs/bcachefs/btree_trans_commit.c:98
 bch2_trans_lock_write+0x669/0xba0 fs/bcachefs/btree_trans_commit.c:134
 do_bch2_trans_commit fs/bcachefs/btree_trans_commit.c:856 [inline]
 __bch2_trans_commit+0x2776/0x8910 fs/bcachefs/btree_trans_commit.c:1089
 bch2_trans_commit fs/bcachefs/btree_update.h:255 [inline]
 check_dirent fs/bcachefs/fsck.c:2413 [inline]
 bch2_check_dirents+0x1c5c/0x33f0 fs/bcachefs/fsck.c:2444
 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:1211
 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

Memory state around the buggy address:
 ffff888047a60000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888047a60080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888047a60100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                         ^
 ffff888047a60180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888047a60200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================