bcachefs (loop0): invalid bkey in superblock btree=extents level=1: u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq c6c25c03258c59c5 written 16 min_key POS_MIN durability: 1 ptr: 0:27:0 gen 0
  pointer before first bucket (27 < 1024), deleting
==================================================================
BUG: KASAN: use-after-free in bucket_gen_get_rcu fs/bcachefs/buckets.h:82 [inline]
BUG: KASAN: use-after-free in dev_ptr_stale_rcu fs/bcachefs/buckets.h:147 [inline]
BUG: KASAN: use-after-free in bch2_extent_ptr_to_text+0x76c/0x770 fs/bcachefs/extents.c:1247
Read of size 1 at addr ffff000136ce9e4e by task syz.0.17/6718

CPU: 1 UID: 0 PID: 6718 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/30/2025
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (C)
 __dump_stack+0x30/0x40 lib/dump_stack.c:94
 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120
 print_address_description+0xa8/0x238 mm/kasan/report.c:378
 print_report+0x68/0x84 mm/kasan/report.c:482
 kasan_report+0xb0/0x110 mm/kasan/report.c:595
 __asan_report_load1_noabort+0x20/0x2c mm/kasan/report_generic.c:378
 bucket_gen_get_rcu fs/bcachefs/buckets.h:82 [inline]
 dev_ptr_stale_rcu fs/bcachefs/buckets.h:147 [inline]
 bch2_extent_ptr_to_text+0x76c/0x770 fs/bcachefs/extents.c:1247
 bch2_bkey_ptrs_to_text+0xcb0/0x13f0 fs/bcachefs/extents.c:1335
 bch2_btree_ptr_v2_to_text+0x198/0x238 fs/bcachefs/extents.c:362
 bch2_val_to_text fs/bcachefs/bkey_methods.c:321 [inline]
 bch2_bkey_val_to_text+0xf0/0x140 fs/bcachefs/bkey_methods.c:331
 __bch2_bkey_fsck_err+0x338/0x4a0 fs/bcachefs/error.c:691
 extent_ptr_validate fs/bcachefs/extents.c:1400 [inline]
 bch2_bkey_ptrs_validate+0x15d0/0x1790 fs/bcachefs/extents.c:1442
 bch2_btree_ptr_v2_validate+0x318/0x5f0 fs/bcachefs/extents.c:345
 bch2_bkey_val_validate fs/bcachefs/bkey_methods.c:143 [inline]
 bch2_bkey_validate+0x1c8/0x2c8 fs/bcachefs/bkey_methods.c:251
 journal_validate_key+0x540/0xc0c fs/bcachefs/journal_io.c:388
 journal_entry_btree_root_validate+0x184/0x4a0 fs/bcachefs/journal_io.c:480
 bch2_journal_entry_validate+0x114/0x188 fs/bcachefs/journal_io.c:874
 bch2_sb_clean_validate_late+0x1c4/0x370 fs/bcachefs/sb-clean.c:44
 bch2_read_superblock_clean+0xbc/0x238 fs/bcachefs/sb-clean.c:172
 bch2_fs_recovery+0x134/0x2fb4 fs/bcachefs/recovery.c:738
 bch2_fs_start+0x940/0xbec fs/bcachefs/super.c:1213
 bch2_fs_get_tree+0x880/0x107c fs/bcachefs/fs.c:2488
 vfs_get_tree+0x90/0x28c fs/super.c:1815
 do_new_mount+0x278/0x7f4 fs/namespace.c:3808
 path_mount+0x5b4/0xde0 fs/namespace.c:4123
 do_mount fs/namespace.c:4136 [inline]
 __do_sys_mount fs/namespace.c:4347 [inline]
 __se_sys_mount fs/namespace.c:4324 [inline]
 __arm64_sys_mount+0x3e8/0x468 fs/namespace.c:4324
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x254 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x5c/0x254 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x12c arch/arm64/kernel/entry-common.c:763
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:596

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x176ce9
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 fffffdffc4db3a48 fffffdffc4db3a48 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff000136ce9d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff000136ce9d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff000136ce9e00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                              ^
 ffff000136ce9e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff000136ce9f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
bcachefs (loop0): invalid bkey in superblock btree=inodes level=1: u64s 11 type btree_ptr_v2 SPOS_MAX len 0 ver 0: seq 7589ab5e0c11cc7a written 24 min_key POS_MIN durability: 1 ptr: 0:1879048230:0 gen 0
  pointer past last bucket (1879048230 > 128), deleting
bcachefs (loop0): invalid journal entry, version=1.7: mi_btree_bitmap type=btree_root in superblock: invalid btree root journal entry: wrong number of keys, shutting down
  error not marked as autofix and not in fsck
  run fsck, and forward to devs so error can be marked for self-healing
  emergency read only at seq 0
bcachefs (loop0): error in recovery: fsck_errors_not_fixed
bcachefs (loop0): bch2_fs_start(): error starting filesystem fsck_errors_not_fixed
bcachefs (loop0): shutting down
bcachefs (loop0): shutdown complete
bcachefs: bch2_fs_get_tree() error: fsck_errors_not_fixed