------------[ cut here ]------------
UBSAN: array-index-out-of-bounds in fs/bcachefs/sb-downgrade.c:272:4
index 0 is out of range for type '__le16[] __counted_by(nr_errors)' (aka 'unsigned short[]')
CPU: 0 UID: 0 PID: 1034 Comm: kworker/u4:5 Not tainted 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #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
Workqueue: btree_update btree_interior_update_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 ubsan_epilogue+0xa/0x40 lib/ubsan.c:231
 __ubsan_handle_out_of_bounds+0xe9/0xf0 lib/ubsan.c:453
 downgrade_table_extra fs/bcachefs/sb-downgrade.c:272 [inline]
 bch2_sb_downgrade_update+0xb10/0xcc0 fs/bcachefs/sb-downgrade.c:392
 bch2_write_super+0xbf2/0x2cd0 fs/bcachefs/super-io.c:1071
 btree_update_new_nodes_mark_sb fs/bcachefs/btree_update_interior.c:608 [inline]
 btree_update_nodes_written fs/bcachefs/btree_update_interior.c:678 [inline]
 btree_interior_update_work+0x441/0x25e0 fs/bcachefs/btree_update_interior.c:843
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
---[ end trace ]---
Kernel panic - not syncing: UBSAN: panic_on_warn set ...
CPU: 0 UID: 0 PID: 1034 Comm: kworker/u4:5 Not tainted 6.15.0-rc5-syzkaller-00043-gd76bb1ebb558 #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
Workqueue: btree_update btree_interior_update_work
Call Trace:
 <TASK>
 dump_stack_lvl+0x99/0x250 lib/dump_stack.c:120
 panic+0x2db/0x790 kernel/panic.c:354
 check_panic_on_warn+0x89/0xb0 kernel/panic.c:243
 __ubsan_handle_out_of_bounds+0xe9/0xf0 lib/ubsan.c:453
 downgrade_table_extra fs/bcachefs/sb-downgrade.c:272 [inline]
 bch2_sb_downgrade_update+0xb10/0xcc0 fs/bcachefs/sb-downgrade.c:392
 bch2_write_super+0xbf2/0x2cd0 fs/bcachefs/super-io.c:1071
 btree_update_new_nodes_mark_sb fs/bcachefs/btree_update_interior.c:608 [inline]
 btree_update_nodes_written fs/bcachefs/btree_update_interior.c:678 [inline]
 btree_interior_update_work+0x441/0x25e0 fs/bcachefs/btree_update_interior.c:843
 process_one_work kernel/workqueue.c:3238 [inline]
 process_scheduled_works+0xadb/0x17a0 kernel/workqueue.c:3319
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3400
 kthread+0x70e/0x8a0 kernel/kthread.c:464
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245
 </TASK>
Kernel Offset: disabled
Rebooting in 86400 seconds..