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BUG: KASAN: out-of-bounds in leaf_insert_into_buf+0x1f4/0x748 fs/reiserfs/lbalance.c:933
Read of size 18446744073709551384 at addr ffff000129088000 by task syz-executor.3/23736

CPU: 0 PID: 23736 Comm: syz-executor.3 Not tainted 6.1.51-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call trace:
 dump_backtrace+0x1c8/0x1f4 arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x108/0x170 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:284 [inline]
 print_report+0x174/0x4c0 mm/kasan/report.c:395
 kasan_report+0xd4/0x130 mm/kasan/report.c:495
 kasan_check_range+0x264/0x2a4 mm/kasan/generic.c:189
 memmove+0x48/0x90 mm/kasan/shadow.c:54
 leaf_insert_into_buf+0x1f4/0x748 fs/reiserfs/lbalance.c:933
 balance_leaf_new_nodes_insert fs/reiserfs/do_balan.c:1001 [inline]
 balance_leaf_new_nodes fs/reiserfs/do_balan.c:1243 [inline]
 balance_leaf+0x61f0/0xe860 fs/reiserfs/do_balan.c:1450
 do_balance+0x27c/0x788 fs/reiserfs/do_balan.c:1888
 reiserfs_insert_item+0x940/0xa84 fs/reiserfs/stree.c:2261
 indirect2direct+0x58c/0xa40 fs/reiserfs/tail_conversion.c:283
 maybe_indirect_to_direct fs/reiserfs/stree.c:1587 [inline]
 reiserfs_cut_from_item+0x854/0x1c98 fs/reiserfs/stree.c:1694
 reiserfs_do_truncate+0x89c/0x11c8 fs/reiserfs/stree.c:1973
 reiserfs_truncate_file+0x510/0xb1c fs/reiserfs/inode.c:2310
 reiserfs_truncate_failed_write fs/reiserfs/inode.c:2743 [inline]
 reiserfs_write_end+0x640/0x800 fs/reiserfs/inode.c:2958
 generic_perform_write+0x384/0x55c mm/filemap.c:3765
 __generic_file_write_iter+0x168/0x388 mm/filemap.c:3882
 generic_file_write_iter+0xb8/0x2b4 mm/filemap.c:3914
 call_write_iter include/linux/fs.h:2205 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x610/0x914 fs/read_write.c:584
 ksys_write+0x15c/0x26c fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __arm64_sys_write+0x7c/0x90 fs/read_write.c:646
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x2c0 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x64/0x218 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x168 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:581

The buggy address belongs to the physical page:
page:00000000feb662b2 refcount:1 mapcount:1 mapping:0000000000000000 index:0xffff669fe pfn:0x169088
memcg:ffff0000c0930000
anon flags: 0x5ffe000000a0014(uptodate|lru|mappedtodisk|swapbacked|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffe000000a0014 fffffc00043f57c8 fffffc0004a14ec8 ffff0000dca1b991
raw: 0000000ffff669fe 0000000000000000 0000000100000000 ffff0000c0930000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff000129087f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff000129087f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff000129088000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff000129088080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff000129088100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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