REISERFS warning (device loop0): vs-13060 reiserfs_update_sd_size: stat data of object [2 6 0x0 SD] (nlink == 1) not found (pos 1)
==================================================================
BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x6a1/0xbd0 fs/reiserfs/lbalance.c:-1
Write of size 4048 at addr ffff88806e1b5030 by task syz.0.17/5931

CPU: 0 PID: 5931 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xac/0x220 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x288/0x290 mm/kasan/generic.c:187
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 leaf_paste_in_buffer+0x6a1/0xbd0 fs/reiserfs/lbalance.c:-1
 balance_leaf_paste_left_whole fs/reiserfs/do_balan.c:564 [inline]
 balance_leaf_paste_left fs/reiserfs/do_balan.c:594 [inline]
 balance_leaf_left fs/reiserfs/do_balan.c:613 [inline]
 balance_leaf+0x3129/0x10da0 fs/reiserfs/do_balan.c:1409
 do_balance+0x2fe/0x940 fs/reiserfs/do_balan.c:1888
 reiserfs_paste_into_item+0x6a1/0x7f0 fs/reiserfs/stree.c:2157
 reiserfs_get_block+0x1bd3/0x3ed0 fs/reiserfs/inode.c:1069
 __block_write_begin_int+0x566/0x1ad0 fs/buffer.c:2124
 reiserfs_write_begin+0x20a/0x4c0 fs/reiserfs/inode.c:2771
 generic_perform_write+0x2fb/0x5b0 mm/filemap.c:4031
 generic_file_write_iter+0xaf/0x2e0 mm/filemap.c:4152
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x43b/0x940 fs/read_write.c:584
 ksys_write+0x147/0x250 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f101318f749
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f101406b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f10133e6090 RCX: 00007f101318f749
RDX: 0000000000000161 RSI: 00002000000005c0 RDI: 0000000000000006
RBP: 00007f1013213f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f10133e6128 R14: 00007f10133e6090 R15: 00007ffd84c7b478
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001b86d40 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x6e1b5
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 ffffea0001b86cc8 ffffea0001b86d88 0000000000000000
raw: 0000000000000001 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), pid 5887, tgid 5887 (udevd), ts 105223578058, free_ts 105299399364
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1cd/0x210 mm/page_alloc.c:1554
 prep_new_page mm/page_alloc.c:1561 [inline]
 get_page_from_freelist+0x195c/0x19f0 mm/page_alloc.c:3191
 __alloc_pages+0x1e3/0x460 mm/page_alloc.c:4457
 __folio_alloc+0x10/0x20 mm/page_alloc.c:4489
 vma_alloc_folio+0x47a/0x8f0 mm/mempolicy.c:2242
 do_anonymous_page mm/memory.c:4150 [inline]
 do_pte_missing mm/memory.c:3687 [inline]
 handle_pte_fault mm/memory.c:5047 [inline]
 __handle_mm_fault mm/memory.c:5188 [inline]
 handle_mm_fault+0x1a38/0x4920 mm/memory.c:5353
 do_user_addr_fault+0x738/0x12e0 arch/x86/mm/fault.c:1373
 handle_page_fault arch/x86/mm/fault.c:1465 [inline]
 exc_page_fault+0x67/0x110 arch/x86/mm/fault.c:1521
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:608
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1154 [inline]
 free_unref_page_prepare+0x7ce/0x8e0 mm/page_alloc.c:2336
 free_unref_page_list+0xbe/0x860 mm/page_alloc.c:2475
 release_pages+0x1fa0/0x2220 mm/swap.c:1022
 tlb_batch_pages_flush mm/mmu_gather.c:98 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
 tlb_flush_mmu+0x368/0x4f0 mm/mmu_gather.c:300
 tlb_finish_mmu+0xc3/0x1d0 mm/mmu_gather.c:392
 unmap_region+0x2ed/0x340 mm/mmap.c:2349
 do_vmi_align_munmap+0xffe/0x1660 mm/mmap.c:2592
 do_vmi_munmap+0x252/0x2d0 mm/mmap.c:2660
 __vm_munmap+0x193/0x3c0 mm/mmap.c:2961
 __do_sys_munmap mm/mmap.c:2978 [inline]
 __se_sys_munmap mm/mmap.c:2975 [inline]
 __x64_sys_munmap+0x60/0x70 mm/mmap.c:2975
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff88806e1b4f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806e1b4f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806e1b5000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                     ^
 ffff88806e1b5080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806e1b5100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================