pointer before first bucket (27 < 1024): delete?, shutting down
bcachefs (loop2): inconsistency detected - emergency read only at journal seq 0
==================================================================
BUG: KASAN: use-after-free in dev_ptr_stale_rcu fs/bcachefs/buckets.h:188 [inline]
BUG: KASAN: use-after-free in bch2_extent_ptr_to_text+0x493/0x4a0 fs/bcachefs/extents.c:1024
Read of size 1 at addr ffff8881907fe04e by task syz.2.17/3327

CPU: 1 UID: 0 PID: 3327 Comm: syz.2.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0xf5/0x170 lib/dump_stack.c:119
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0xca/0x250 mm/kasan/report.c:488
 kasan_report+0x118/0x150 mm/kasan/report.c:601
 dev_ptr_stale_rcu fs/bcachefs/buckets.h:188 [inline]
 bch2_extent_ptr_to_text+0x493/0x4a0 fs/bcachefs/extents.c:1024
 bch2_bkey_ptrs_to_text+0x813/0xc70 fs/bcachefs/extents.c:1062
 __bch2_bkey_fsck_err+0xf8/0x1f0 fs/bcachefs/error.c:429
 bch2_bkey_ptrs_validate+0xdb1/0x12b0 fs/bcachefs/extents.c:-1
 journal_validate_key+0x429/0xa20 fs/bcachefs/journal_io.c:370
 journal_entry_btree_root_validate+0xff/0x3f0 fs/bcachefs/journal_io.c:455
 bch2_sb_clean_validate_late fs/bcachefs/sb-clean.c:40 [inline]
 bch2_read_superblock_clean+0x18a/0x3c0 fs/bcachefs/sb-clean.c:168
 bch2_fs_recovery+0x144/0x27f0 fs/bcachefs/recovery.c:632
 bch2_fs_start+0x2fa/0x4d0 fs/bcachefs/super.c:1036
 bch2_fs_get_tree+0x467/0xf90 fs/bcachefs/fs.c:1946
 vfs_get_tree+0x84/0x1a0 fs/super.c:1800
 do_new_mount+0x1c9/0x850 fs/namespace.c:3472
 do_mount fs/namespace.c:3812 [inline]
 __do_sys_mount fs/namespace.c:4020 [inline]
 __se_sys_mount+0x21c/0x2c0 fs/namespace.c:3997
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x8f/0x180 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f95fea6066a
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:00007f95fe0cde68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f95fe0cdef0 RCX: 00007f95fea6066a
RDX: 0000200000005b40 RSI: 0000200000000000 RDI: 00007f95fe0cdeb0
RBP: 0000200000005b40 R08: 00007f95fe0cdef0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000000
R13: 00007f95fe0cdeb0 R14: 000000000000594b R15: 0000200000000080
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1907fe
flags: 0x100000000000000(node=0|zone=2)
raw: 0100000000000000 ffffea000641ff88 ffffea000641ff88 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:
 ffff8881907fdf00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881907fdf80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881907fe000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff8881907fe080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881907fe100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================