==================================================================
BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x1a8/0x9f0 fs/reiserfs/lbalance.c:1017
Write of size 3936 at addr ffff0000f03e7140 by task syz.6.285/5551

CPU: 1 PID: 5551 Comm: syz.6.285 Not tainted 5.15.177-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call trace:
 dump_backtrace+0x0/0x530 arch/arm64/kernel/stacktrace.c:152
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 print_address_description+0x7c/0x3f0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0x174/0x1e4 mm/kasan/report.c:451
 kasan_check_range+0x274/0x2b4 mm/kasan/generic.c:189
 memmove+0xb4/0xe8 mm/kasan/shadow.c:55
 leaf_paste_in_buffer+0x1a8/0x9f0 fs/reiserfs/lbalance.c:1017
 leaf_copy_boundary_item+0x96c/0x1a34 fs/reiserfs/lbalance.c:199
 leaf_copy_items fs/reiserfs/lbalance.c:551 [inline]
 leaf_move_items+0xa0c/0x1f7c fs/reiserfs/lbalance.c:726
 leaf_shift_left+0xc8/0x39c fs/reiserfs/lbalance.c:750
 balance_leaf_paste_left_shift fs/reiserfs/do_balan.c:458 [inline]
 balance_leaf_paste_left fs/reiserfs/do_balan.c:592 [inline]
 balance_leaf_left fs/reiserfs/do_balan.c:613 [inline]
 balance_leaf+0x41c0/0xe860 fs/reiserfs/do_balan.c:1409
 do_balance+0x27c/0x790 fs/reiserfs/do_balan.c:1888
 reiserfs_paste_into_item+0x630/0x744 fs/reiserfs/stree.c:2159
 reiserfs_get_block+0x1820/0x3fd0 fs/reiserfs/inode.c:1077
 __block_write_begin_int+0x3ec/0x1608 fs/buffer.c:2012
 __block_write_begin+0x40/0x54 fs/buffer.c:2062
 reiserfs_write_begin+0x3c8/0x654 fs/reiserfs/inode.c:2790
 generic_perform_write+0x24c/0x520 mm/filemap.c:3785
 __generic_file_write_iter+0x230/0x454 mm/filemap.c:3912
 generic_file_write_iter+0xb4/0x1b8 mm/filemap.c:3944
 do_iter_readv_writev+0x420/0x5f8
 do_iter_write+0x1b8/0x66c fs/read_write.c:855
 vfs_writev fs/read_write.c:928 [inline]
 do_pwritev+0x1ec/0x334 fs/read_write.c:1025
 __do_sys_pwritev2 fs/read_write.c:1084 [inline]
 __se_sys_pwritev2 fs/read_write.c:1075 [inline]
 __arm64_sys_pwritev2+0xd4/0x108 fs/read_write.c:1075
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181
 el0_svc+0x7c/0x1f0 arch/arm64/kernel/entry-common.c:608
 el0t_64_sync_handler+0x84/0xe4 arch/arm64/kernel/entry-common.c:626
 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584

The buggy address belongs to the page:
page:00000000fa646f23 refcount:0 mapcount:0 mapping:0000000000000000 index:0x100 pfn:0x1303e7
flags: 0x5ffc00000000000(node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffc00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000100 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000f03e7000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f03e7080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff0000f03e7100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff0000f03e7180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000f03e7200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
Unable to handle kernel write to read-only memory at virtual address ffff0000f7ad3000