==================================================================
BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x5d0/0xa40 fs/reiserfs/lbalance.c:1043
Read of size 48 at addr ffff0000f7477ff0 by task syz.4.33/4560

CPU: 1 PID: 4560 Comm: syz.4.33 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026
Call trace:
 dump_backtrace+0x1c4/0x1f0 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x258/0x290 mm/kasan/generic.c:189
 memcpy+0x48/0x90 mm/kasan/shadow.c:65
 leaf_paste_in_buffer+0x5d0/0xa40 fs/reiserfs/lbalance.c:1043
 leaf_copy_dir_entries+0x444/0x780 fs/reiserfs/lbalance.c:108
 leaf_copy_boundary_item+0x87c/0x19f4 fs/reiserfs/lbalance.c:-1
 leaf_copy_items fs/reiserfs/lbalance.c:551 [inline]
 leaf_move_items+0x6c8/0xbd8 fs/reiserfs/lbalance.c:726
 balance_leaf_when_delete_left fs/reiserfs/do_balan.c:167 [inline]
 balance_leaf_when_delete fs/reiserfs/do_balan.c:272 [inline]
 balance_leaf+0x9800/0xdee0 fs/reiserfs/do_balan.c:1393
 do_balance+0x270/0x794 fs/reiserfs/do_balan.c:1888
 reiserfs_cut_from_item+0x1160/0x1a34 fs/reiserfs/stree.c:1838
 reiserfs_do_truncate+0x728/0xfd0 fs/reiserfs/stree.c:1973
 reiserfs_truncate_file+0x3a4/0xb04 fs/reiserfs/inode.c:2310
 reiserfs_setattr+0xad4/0x1014 fs/reiserfs/inode.c:3395
 notify_change+0xb5c/0xe20 fs/attr.c:499
 do_truncate+0x188/0x20c fs/open.c:65
 do_sys_ftruncate+0x284/0x318 fs/open.c:193
 __do_sys_ftruncate fs/open.c:204 [inline]
 __se_sys_ftruncate fs/open.c:202 [inline]
 __arm64_sys_ftruncate+0x60/0x74 fs/open.c:202
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x13c/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x5c/0x134 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 arch/arm64/kernel/entry-common.c:637
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:655
 el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:585

The buggy address belongs to the physical page:
page:00000000b02d9f99 refcount:2 mapcount:0 mapping:00000000b82103d3 index:0x234 pfn:0x137477
memcg:ffff0000cd528000
aops:def_blk_aops ino:700004
flags: 0x5ffd6000000205a(referenced|dirty|lru|workingset|private|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffd6000000205a fffffc0003dd1d88 fffffc0003d98648 ffff0000c51beb18
raw: 0000000000000234 ffff0000f9a6d910 00000002ffffffff ffff0000cd528000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f7477f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000f7477f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000f7478000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff0000f7478080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f7478100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
REISERFS error (device loop4): vs-4010 is_reusable: block number is out of range 11822 (1024)
REISERFS (device loop4): Remounting filesystem read-only
REISERFS error (device loop4): vs-4010 is_reusable: block number is out of range 265880 (1024)
REISERFS error (device loop4): vs-4010 is_reusable: block number is out of range 593568 (1024)
REISERFS error (device loop4): vs-4080 _reiserfs_free_block: block 1: bit already cleared
REISERFS warning (device loop4): clm-6006 reiserfs_dirty_inode: writing inode 5 on readonly FS