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,background_compression=gzip,wide_macs,grpquota,nojournal_transaction_names
  allowing incompatible features above 0.0: (unknown version)
bcachefs (loop0): invalid bkey in superblock btree=extents level=0: u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 4e0410879b0c2f04 written 16 min_key POS_MIN durability: 1 ptr: 0:27:0 gen 0
  invalid key type for btree extents (btree_ptr_v2), deleting
bcachefs (loop0): recovering from clean shutdown, journal seq 13
bcachefs (loop0): Version upgrade required:
Version upgrade from 0.19: freespace to 1.7: mi_btree_bitmap incomplete
Doing incompatible version upgrade from 0.19: freespace to 1.25: extent_flags
  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
==================================================================
BUG: KASAN: use-after-free in poly1305_update include/crypto/poly1305.h:83 [inline]
BUG: KASAN: use-after-free in bch2_checksum+0x209/0x490 fs/bcachefs/checksum.c:157
Read of size 8 at addr ffff888053d79020 by task syz.0.0/5312

CPU: 0 UID: 0 PID: 5312 Comm: syz.0.0 Not tainted 6.15.0-rc4-syzkaller-00052-g4f79eaa2ceac #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:408 [inline]
 print_report+0xb4/0x290 mm/kasan/report.c:521
 kasan_report+0x118/0x150 mm/kasan/report.c:634
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x29a/0x2b0 mm/kasan/generic.c:189
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 poly1305_update include/crypto/poly1305.h:83 [inline]
 bch2_checksum+0x209/0x490 fs/bcachefs/checksum.c:157
 bch2_btree_node_read_done+0x1003/0x5470 fs/bcachefs/btree_io.c:1132
 btree_node_read_work+0x565/0xef0 fs/bcachefs/btree_io.c:1366
 bch2_btree_node_read+0x2151/0x27a0 fs/bcachefs/btree_io.c:-1
 __bch2_btree_root_read fs/bcachefs/btree_io.c:1797 [inline]
 bch2_btree_root_read+0x5e7/0x750 fs/bcachefs/btree_io.c:1819
 read_btree_roots+0x2cb/0x800 fs/bcachefs/recovery.c:582
 bch2_fs_recovery+0x2356/0x37b0 fs/bcachefs/recovery.c:929
 bch2_fs_start+0x70b/0xae0 fs/bcachefs/super.c:1083
 bch2_fs_get_tree+0xd99/0x1340 fs/bcachefs/fs.c:2570
 vfs_get_tree+0x8f/0x2b0 fs/super.c:1759
 do_new_mount+0x24a/0xa40 fs/namespace.c:3884
 do_mount fs/namespace.c:4224 [inline]
 __do_sys_mount fs/namespace.c:4435 [inline]
 __se_sys_mount+0x317/0x410 fs/namespace.c:4412
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f744699010a
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:00007f74477fde68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f74477fdef0 RCX: 00007f744699010a
RDX: 000020000000f640 RSI: 0000200000000200 RDI: 00007f74477fdeb0
RBP: 000020000000f640 R08: 00007f74477fdef0 R09: 0000000002a08410
R10: 0000000002a08410 R11: 0000000000000246 R12: 0000200000000200
R13: 00007f74477fdeb0 R14: 000000000000f62f R15: 0000200000000440
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x53d79
flags: 0x4fff00000000000(node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner info is not present (never set?)

Memory state around the buggy address:
 ffff888053d78f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888053d78f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888053d79000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff888053d79080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888053d79100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================