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BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x1b8/0xab0 fs/reiserfs/lbalance.c:1017
Write of size 3936 at addr ffff8880528ec140 by task syz.1.212/5077

CPU: 1 PID: 5077 Comm: syz.1.212 Not tainted 6.1.118-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:284 [inline]
 print_report+0x15f/0x4f0 mm/kasan/report.c:395
 kasan_report+0x136/0x160 mm/kasan/report.c:495
 kasan_check_range+0x27f/0x290 mm/kasan/generic.c:189
 memmove+0x3c/0x60 mm/kasan/shadow.c:55
 leaf_paste_in_buffer+0x1b8/0xab0 fs/reiserfs/lbalance.c:1017
 leaf_copy_boundary_item+0xcbf/0x21b0 fs/reiserfs/lbalance.c:199
 leaf_copy_items fs/reiserfs/lbalance.c:551 [inline]
 leaf_move_items+0xcd0/0x28a0 fs/reiserfs/lbalance.c:726
 leaf_shift_left+0xba/0x430 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+0x3071/0x12510 fs/reiserfs/do_balan.c:1409
 do_balance+0x309/0x8f0 fs/reiserfs/do_balan.c:1888
 reiserfs_paste_into_item+0x73b/0x880 fs/reiserfs/stree.c:2159
 reiserfs_get_block+0x2259/0x5150 fs/reiserfs/inode.c:1069
 __block_write_begin_int+0x544/0x1a30 fs/buffer.c:1991
 reiserfs_write_begin+0x249/0x510 fs/reiserfs/inode.c:2775
 generic_perform_write+0x2fc/0x5e0 mm/filemap.c:3845
 __generic_file_write_iter+0x176/0x400 mm/filemap.c:3973
 generic_file_write_iter+0xab/0x310 mm/filemap.c:4005
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x857/0xbc0 fs/read_write.c:584
 ksys_pwrite64 fs/read_write.c:699 [inline]
 __do_sys_pwrite64 fs/read_write.c:709 [inline]
 __se_sys_pwrite64 fs/read_write.c:706 [inline]
 __x64_sys_pwrite64+0x1a6/0x230 fs/read_write.c:706
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f181777e819
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:00007f1818606038 EFLAGS: 00000246 ORIG_RAX: 0000000000000012
RAX: ffffffffffffffda RBX: 00007f1817935fa0 RCX: 00007f181777e819
RDX: 0000000000000001 RSI: 0000000020000140 RDI: 0000000000000006
RBP: 00007f18177f175e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000008000c61 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f1817935fa0 R15: 00007ffc2586b978
 </TASK>

The buggy address belongs to the physical page:
page:ffffea00014a3b00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x528ec
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00014aae48 ffffea00014721c8 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5107, tgid 5107 (modprobe), ts 123795980330, free_ts 123980044485
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x18d/0x1b0 mm/page_alloc.c:2517
 prep_new_page mm/page_alloc.c:2524 [inline]
 get_page_from_freelist+0x3731/0x38d0 mm/page_alloc.c:4313
 __alloc_pages+0x28d/0x770 mm/page_alloc.c:5589
 __folio_alloc+0xf/0x30 mm/page_alloc.c:5621
 vma_alloc_folio+0x486/0x990 mm/mempolicy.c:2243
 alloc_page_vma include/linux/gfp.h:284 [inline]
 do_cow_fault mm/memory.c:4648 [inline]
 do_fault mm/memory.c:4760 [inline]
 handle_pte_fault mm/memory.c:5029 [inline]
 __handle_mm_fault mm/memory.c:5171 [inline]
 handle_mm_fault+0x210c/0x5340 mm/memory.c:5292
 do_user_addr_fault arch/x86/mm/fault.c:1340 [inline]
 handle_page_fault arch/x86/mm/fault.c:1431 [inline]
 exc_page_fault+0x26f/0x620 arch/x86/mm/fault.c:1487
 asm_exc_page_fault+0x22/0x30 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:1444 [inline]
 free_pcp_prepare mm/page_alloc.c:1494 [inline]
 free_unref_page_prepare+0xf63/0x1120 mm/page_alloc.c:3369
 free_unref_page_list+0x663/0x900 mm/page_alloc.c:3510
 release_pages+0x2836/0x2b40 mm/swap.c:1055
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
 tlb_flush_mmu+0xfc/0x210 mm/mmu_gather.c:261
 tlb_finish_mmu+0xce/0x1f0 mm/mmu_gather.c:361
 exit_mmap+0x3c3/0x9f0 mm/mmap.c:3239
 __mmput+0x115/0x3c0 kernel/fork.c:1200
 exit_mm+0x226/0x300 kernel/exit.c:565
 do_exit+0x9f6/0x26a0 kernel/exit.c:858
 do_group_exit+0x202/0x2b0 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1030
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff8880528ec000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880528ec080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880528ec100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff8880528ec180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880528ec200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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