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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 ffff88805c080140 by task syz.1.2114/15725

CPU: 0 PID: 15725 Comm: syz.1.2114 Not tainted 5.15.173-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 print_address_description+0x63/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0x16b/0x1c0 mm/kasan/report.c:451
 kasan_check_range+0x27e/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+0x226a/0x5390 fs/reiserfs/inode.c:1077
 __block_write_begin_int+0x60b/0x1650 fs/buffer.c:2012
 reiserfs_write_begin+0x346/0x810 fs/reiserfs/inode.c:2790
 generic_cont_expand_simple+0x144/0x230 fs/buffer.c:2362
 reiserfs_setattr+0x3ff/0xf90 fs/reiserfs/inode.c:3319
 notify_change+0xc6d/0xf50 fs/attr.c:505
 do_truncate+0x21c/0x300 fs/open.c:65
 do_sys_ftruncate+0x2eb/0x390 fs/open.c:193
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f1496b64849
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:00007f14949b9058 EFLAGS: 00000246 ORIG_RAX: 000000000000004d
RAX: ffffffffffffffda RBX: 00007f1496d2a080 RCX: 00007f1496b64849
RDX: 0000000000000000 RSI: 0000000002000009 RDI: 000000000000000e
RBP: 00007f1496bd7986 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f1496d2a080 R15: 00007fff9e9cbca8
 </TASK>

The buggy address belongs to the page:
page:ffffea0001702000 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x5c080
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001500ec8 ffffea00014a91c8 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 0x1100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 15726, ts 916606366190, free_ts 916707919042
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x3b78/0x3d40 mm/page_alloc.c:4192
 __alloc_pages+0x272/0x700 mm/page_alloc.c:5464
 alloc_pages_vma+0x39a/0x800 mm/mempolicy.c:2146
 do_anonymous_page mm/memory.c:3836 [inline]
 handle_pte_fault mm/memory.c:4646 [inline]
 __handle_mm_fault mm/memory.c:4783 [inline]
 handle_mm_fault+0x2f49/0x5960 mm/memory.c:4881
 do_user_addr_fault arch/x86/mm/fault.c:1357 [inline]
 handle_page_fault arch/x86/mm/fault.c:1445 [inline]
 exc_page_fault+0x271/0x700 arch/x86/mm/fault.c:1501
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0xc34/0xcf0 mm/page_alloc.c:3317
 free_unref_page_list+0x1f7/0x8e0 mm/page_alloc.c:3433
 release_pages+0x1bb9/0x1f40 mm/swap.c:963
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:240 [inline]
 tlb_flush_mmu mm/mmu_gather.c:247 [inline]
 tlb_finish_mmu+0x177/0x320 mm/mmu_gather.c:338
 unmap_region+0x304/0x350 mm/mmap.c:2668
 __do_munmap+0x12db/0x1740 mm/mmap.c:2899
 __vm_munmap+0x134/0x230 mm/mmap.c:2922
 __do_sys_munmap mm/mmap.c:2948 [inline]
 __se_sys_munmap mm/mmap.c:2944 [inline]
 __x64_sys_munmap+0x67/0x70 mm/mmap.c:2944
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88805c080000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805c080080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88805c080100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff88805c080180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805c080200: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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