==================================================================
BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x66c/0xa14 fs/reiserfs/lbalance.c:-1
Read of size 48 at addr ffff0000dbb69ff0 by task syz.0.140/5364

CPU: 0 PID: 5364 Comm: syz.0.140 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call trace:
 dump_backtrace+0x1c0/0x1ec 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+0x66c/0xa14 fs/reiserfs/lbalance.c:-1
 leaf_copy_dir_entries+0x45c/0x788 fs/reiserfs/lbalance.c:108
 leaf_copy_boundary_item+0x888/0x19dc fs/reiserfs/lbalance.c:-1
 leaf_copy_items fs/reiserfs/lbalance.c:551 [inline]
 leaf_move_items+0x6a0/0xbb0 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+0x9794/0xd92c fs/reiserfs/do_balan.c:1393
 do_balance+0x270/0x790 fs/reiserfs/do_balan.c:1888
 reiserfs_cut_from_item+0x114c/0x1a14 fs/reiserfs/stree.c:1838
 reiserfs_do_truncate+0x738/0x1058 fs/reiserfs/stree.c:1973
 reiserfs_truncate_file+0x5d0/0xb00 fs/reiserfs/inode.c:2310
 reiserfs_setattr+0xab4/0xfec fs/reiserfs/inode.c:3395
 notify_change+0xb0c/0xdcc fs/attr.c:499
 do_truncate+0x188/0x20c fs/open.c:65
 handle_truncate fs/namei.c:3293 [inline]
 do_open fs/namei.c:3638 [inline]
 path_openat+0x2110/0x26bc fs/namei.c:3791
 do_filp_open+0x194/0x384 fs/namei.c:3818
 do_sys_openat2+0x134/0x3f4 fs/open.c:1320
 do_sys_open fs/open.c:1336 [inline]
 __do_sys_openat fs/open.c:1352 [inline]
 __se_sys_openat fs/open.c:1347 [inline]
 __arm64_sys_openat+0x118/0x14c fs/open.c:1347
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b4 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 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:000000000eae81a2 refcount:2 mapcount:0 mapping:0000000000bd913f index:0x234 pfn:0x11bb69
memcg:ffff0000cb58a000
aops:def_blk_aops ino:700000
flags: 0x5ffd60000002052(referenced|lru|workingset|private|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffd60000002052 fffffc0003e00408 fffffc00036ed748 ffff0000c049ca10
raw: 0000000000000234 ffff0000e244abc8 00000002ffffffff ffff0000cb58a000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000dbb69f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000dbb69f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000dbb6a000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff0000dbb6a080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000dbb6a100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
REISERFS error (device loop0): vs-4010 is_reusable: block number is out of range 11822 (1024)
REISERFS (device loop0): Remounting filesystem read-only
REISERFS error (device loop0): vs-4010 is_reusable: block number is out of range 265880 (1024)
REISERFS error (device loop0): vs-4010 is_reusable: block number is out of range 593568 (1024)
REISERFS error (device loop0): vs-4080 _reiserfs_free_block: block 1: bit already cleared
REISERFS error (device loop0): vs-4080 _reiserfs_free_block: block 1: bit already cleared
REISERFS warning (device loop0): clm-6006 reiserfs_dirty_inode: writing inode 5 on readonly FS