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BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x66c/0xa14 fs/reiserfs/lbalance.c:-1
Read of size 48 at addr ffff0000d65ffff0 by task syz.2.268/5590

CPU: 0 PID: 5590 Comm: syz.2.268 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
Call trace:
 dump_backtrace+0x1c0/0x1ec arch/arm64/kernel/stacktrace.c:158
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:165
 __dump_stack+0x30/0x40 lib/dump_stack.c:88
 dump_stack_lvl+0xf4/0x15c lib/dump_stack.c:106
 print_address_description+0x88/0x218 mm/kasan/report.c:316
 print_report+0x50/0x68 mm/kasan/report.c:420
 kasan_report+0xa8/0xfc mm/kasan/report.c:524
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x258/0x290 mm/kasan/generic.c:189
 memcpy+0x48/0x90 mm/kasan/shadow.c:65
 leaf_paste_in_buffer+0x66c/0xa14 fs/reiserfs/lbalance.c:-1
 leaf_copy_dir_entries+0x45c/0x788 fs/reiserfs/lbalance.c:108
 leaf_copy_boundary_item+0x888/0x19dc fs/reiserfs/lbalance.c:-1
 leaf_copy_items fs/reiserfs/lbalance.c:551 [inline]
 leaf_move_items+0x6a0/0xbb0 fs/reiserfs/lbalance.c:726
 leaf_shift_left+0xc8/0x3ac fs/reiserfs/lbalance.c:750
 balance_leaf_when_delete_left fs/reiserfs/do_balan.c:194 [inline]
 balance_leaf_when_delete fs/reiserfs/do_balan.c:272 [inline]
 balance_leaf+0x27b0/0xd92c fs/reiserfs/do_balan.c:1393
 do_balance+0x270/0x790 fs/reiserfs/do_balan.c:1888
 reiserfs_delete_item+0x8fc/0xc94 fs/reiserfs/stree.c:1371
 direct2indirect+0x7d4/0xec4 fs/reiserfs/tail_conversion.c:139
 reiserfs_get_block+0x31fc/0x36e8 fs/reiserfs/inode.c:949
 __block_write_begin_int+0x350/0x1388 fs/buffer.c:1991
 __block_write_begin+0x7c/0xa0 fs/buffer.c:2041
 reiserfs_write_begin+0x328/0x714 fs/reiserfs/inode.c:2775
 generic_perform_write+0x234/0x4f4 mm/filemap.c:3862
 __generic_file_write_iter+0x130/0x250 mm/filemap.c:3960
 generic_file_write_iter+0xb4/0x2b0 mm/filemap.c:3989
 call_write_iter include/linux/fs.h:2265 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x3ec/0x7f0 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]
 __arm64_sys_pwrite64+0x174/0x20c fs/read_write.c:706
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x98/0x290 arch/arm64/kernel/syscall.c:52
 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:140
 do_el0_svc+0x58/0x130 arch/arm64/kernel/syscall.c:204
 el0_svc+0x58/0x128 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:585

The buggy address belongs to the physical page:
page:00000000595b2564 refcount:2 mapcount:0 mapping:00000000838d067a index:0x3f8 pfn:0x1165ff
memcg:ffff0000c0940000
aops:def_blk_aops ino:700002
flags: 0x5ffd60000022056(referenced|uptodate|lru|workingset|private|mappedtodisk|node=0|zone=2|lastcpupid=0x7ff)
raw: 05ffd60000022056 fffffc0003369888 fffffc0003f04288 ffff0000c049e018
raw: 00000000000003f8 ffff0000ca087910 00000002ffffffff ffff0000c0940000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff0000d65fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff0000d65fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff0000d6600000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff0000d6600080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff0000d6600100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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