loop0: detected capacity change from 0 to 32768
bcachefs (loop0): starting version 1.7: mi_btree_bitmap opts=errors=continue,metadata_checksum=none,data_checksum=none,compression=lz4,nojournal_transaction_names
bcachefs (loop0): recovering from clean shutdown, journal seq 10
bcachefs (loop0): Version upgrade required:
Version upgrade from 0.24: unwritten_extents to 1.7: mi_btree_bitmap incomplete
Doing incompatible version upgrade from 0.24: unwritten_extents to 1.13: inode_has_child_snapshots
  running recovery passes: check_allocations,check_alloc_info,check_lrus,check_btree_backpointers,check_backpointers_to_extents,check_extents_to_backpointers,check_alloc_to_lru_refs,bucket_gens_init,check_snapshot_trees,check_snapshots,check_subvols,check_subvol_children,delete_dead_snapshots,check_inodes,check_extents,check_indirect_extents,check_dirents,check_xattrs,check_root,check_unreachable_inodes,check_subvolume_structure,check_directory_structure,check_nlinks,set_fs_needs_rebalance
bcachefs (loop0): error validating btree node on loop0 at btree dirents level 0/0
  u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 9aa2895aefce4bdf written 24 min_key POS_MIN durability: 1 ptr: 0:41:0 gen 0  
  node offset 16/24: btree node data missing: expected 24 sectors, found 16, fixing
bcachefs (loop0): btree_node_read_work: rewriting btree node at btree=dirents level=0 SPOS_MAX due to error
bcachefs (loop0): error validating btree node at btree alloc level 0/0
  u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq ac62141f8dc7e261 written 24 min_key POS_MIN durability: 1 ptr: 0:26:0 gen 0  
  node offset 8/24 bset u64s 375 bset byte offset 184: keys out of order: u64s 11 type alloc_v4 0:32:0 len 0 ver 0 > u64s 11 type alloc_v4 0:2:0 len 0 ver 0, fixing
bcachefs (loop0): btree_node_read_work: rewriting btree node at btree=alloc level=0 SPOS_MAX due to error
==================================================================
BUG: KASAN: use-after-free in bch2_btree_node_read_done+0xfbe/0x5e90 fs/bcachefs/btree_io.c:1087
Read of size 8 at addr ffff888045578010 by task syz.0.0/5333

CPU: 0 UID: 0 PID: 5333 Comm: syz.0.0 Not tainted 6.12.0-syzkaller-09073-g9f16d5e6f220 #0
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 lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 bch2_btree_node_read_done+0xfbe/0x5e90 fs/bcachefs/btree_io.c:1087
 btree_node_read_work+0x68b/0x1260 fs/bcachefs/btree_io.c:1323
 bch2_btree_node_read+0x2433/0x2a10
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1749 [inline]
 bch2_btree_root_read+0x617/0x7a0 fs/bcachefs/btree_io.c:1771
 read_btree_roots+0x296/0x840 fs/bcachefs/recovery.c:523
 bch2_fs_recovery+0x2585/0x39d0 fs/bcachefs/recovery.c:853
 bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1037
 bch2_fs_get_tree+0xd68/0x1710 fs/bcachefs/fs.c:2170
 vfs_get_tree+0x90/0x2b0 fs/super.c:1814
 do_new_mount+0x2be/0xb40 fs/namespace.c:3507
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4057 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4034
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc95957ffba
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:00007fc95a432e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fc95a432ef0 RCX: 00007fc95957ffba
RDX: 00000000200000c0 RSI: 0000000020000080 RDI: 00007fc95a432eb0
RBP: 00000000200000c0 R08: 00007fc95a432ef0 R09: 0000000000000010
R10: 0000000000000010 R11: 0000000000000246 R12: 0000000020000080
R13: 00007fc95a432eb0 R14: 0000000000005955 R15: 0000000020000480
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x45578
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 ffffea0001155f08 ffff88801fc44a60 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 2, migratetype Reclaimable, gfp_mask 0x452cd0(GFP_KERNEL_ACCOUNT|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_RECLAIMABLE), pid 5333, tgid 5332 (syz.0.0), ts 73735681521, free_ts 73846584716
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1556
 prep_new_page mm/page_alloc.c:1564 [inline]
 get_page_from_freelist+0x3649/0x3790 mm/page_alloc.c:3474
 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4751
 __alloc_pages_node_noprof include/linux/gfp.h:269 [inline]
 alloc_pages_node_noprof include/linux/gfp.h:296 [inline]
 ___kmalloc_large_node+0x8b/0x1d0 mm/slub.c:4209
 __kmalloc_large_node_noprof+0x1a/0x80 mm/slub.c:4236
 __do_kmalloc_node mm/slub.c:4252 [inline]
 __kmalloc_node_noprof+0x2d2/0x440 mm/slub.c:4270
 __kvmalloc_node_noprof+0x72/0x190 mm/util.c:658
 btree_node_data_alloc+0xdb/0x260 fs/bcachefs/btree_cache.c:153
 __bch2_btree_node_mem_alloc+0x1d8/0x3e0 fs/bcachefs/btree_cache.c:198
 bch2_fs_btree_cache_init+0x26f/0x630 fs/bcachefs/btree_cache.c:653
 bch2_fs_alloc fs/bcachefs/super.c:917 [inline]
 bch2_fs_open+0x2aa4/0x2f80 fs/bcachefs/super.c:2065
 bch2_fs_get_tree+0x738/0x1710 fs/bcachefs/fs.c:2157
 vfs_get_tree+0x90/0x2b0 fs/super.c:1814
 do_new_mount+0x2be/0xb40 fs/namespace.c:3507
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4057 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4034
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
page last free pid 5333 tgid 5332 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0xdf9/0x1140 mm/page_alloc.c:2657
 __folio_put+0x2c7/0x440 mm/swap.c:112
 folio_put include/linux/mm.h:1488 [inline]
 free_large_kmalloc+0x105/0x1c0 mm/slub.c:4698
 kfree+0x21c/0x440 mm/slub.c:4721
 btree_bounce_free fs/bcachefs/btree_io.c:112 [inline]
 bch2_btree_node_read_done+0x3c8a/0x5e90 fs/bcachefs/btree_io.c:1209
 btree_node_read_work+0x68b/0x1260 fs/bcachefs/btree_io.c:1323
 bch2_btree_node_read+0x2433/0x2a10
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1749 [inline]
 bch2_btree_root_read+0x617/0x7a0 fs/bcachefs/btree_io.c:1771
 read_btree_roots+0x296/0x840 fs/bcachefs/recovery.c:523
 bch2_fs_recovery+0x2585/0x39d0 fs/bcachefs/recovery.c:853
 bch2_fs_start+0x356/0x5b0 fs/bcachefs/super.c:1037
 bch2_fs_get_tree+0xd68/0x1710 fs/bcachefs/fs.c:2170
 vfs_get_tree+0x90/0x2b0 fs/super.c:1814
 do_new_mount+0x2be/0xb40 fs/namespace.c:3507
 do_mount fs/namespace.c:3847 [inline]
 __do_sys_mount fs/namespace.c:4057 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4034
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83

Memory state around the buggy address:
 ffff888045577f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888045577f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888045578000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                         ^
 ffff888045578080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888045578100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================