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BUG: KASAN: use-after-free in leaf_paste_in_buffer+0x631/0xab0
Read of size 48 at addr ffff888060a26ff0 by task syz-executor.4/4745

CPU: 0 PID: 4745 Comm: syz-executor.4 Not tainted 6.1.59-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
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
 memcpy+0x25/0x60 mm/kasan/shadow.c:65
 leaf_paste_in_buffer+0x631/0xab0
 leaf_copy_dir_entries+0x71a/0xc60 fs/reiserfs/lbalance.c:108
 leaf_copy_boundary_item+0xbbe/0x21b0 fs/reiserfs/lbalance.c:168
 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_when_delete_left fs/reiserfs/do_balan.c:194 [inline]
 balance_leaf_when_delete fs/reiserfs/do_balan.c:272 [inline]
 balance_leaf+0x228e/0x12510 fs/reiserfs/do_balan.c:1393
 do_balance+0x309/0x8f0 fs/reiserfs/do_balan.c:1888
 reiserfs_cut_from_item+0x1945/0x2580 fs/reiserfs/stree.c:1838
 reiserfs_do_truncate+0xa12/0x15b0 fs/reiserfs/stree.c:1973
 reiserfs_truncate_file+0x4d6/0x810 fs/reiserfs/inode.c:2310
 reiserfs_setattr+0xc57/0x11c0 fs/reiserfs/inode.c:3395
 notify_change+0xce3/0xfc0 fs/attr.c:499
 do_truncate+0x21c/0x300 fs/open.c:65
 handle_truncate fs/namei.c:3216 [inline]
 do_open fs/namei.c:3561 [inline]
 path_openat+0x27e2/0x2e60 fs/namei.c:3714
 do_filp_open+0x230/0x480 fs/namei.c:3741
 do_sys_openat2+0x13b/0x500 fs/open.c:1318
 do_sys_open fs/open.c:1334 [inline]
 __do_sys_creat fs/open.c:1410 [inline]
 __se_sys_creat fs/open.c:1404 [inline]
 __x64_sys_creat+0x11f/0x160 fs/open.c:1404
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fca4187cae9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fca4259e0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007fca4199bf80 RCX: 00007fca4187cae9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 00000000200000c0
RBP: 00007fca418c847a R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007fca4199bf80 R15: 00007fff5c86e9f8
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001828980 refcount:2 mapcount:0 mapping:ffff888148cdf5f8 index:0x21c pfn:0x60a26
memcg:ffff88807ad70000
aops:def_blk_aops ino:700004
flags: 0xfff38000002052(referenced|lru|workingset|private|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff38000002052 ffffea00017c6a48 ffffea00019ec188 ffff888148cdf5f8
raw: 000000000000021c ffff8880742dcbc8 00000002ffffffff ffff88807ad70000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x148c48(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL|__GFP_MOVABLE), pid 4745, tgid 4744 (syz-executor.4), ts 278986950534, free_ts 278925362508
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x18d/0x1b0 mm/page_alloc.c:2513
 prep_new_page mm/page_alloc.c:2520 [inline]
 get_page_from_freelist+0x31a1/0x3320 mm/page_alloc.c:4279
 __alloc_pages+0x28d/0x770 mm/page_alloc.c:5545
 folio_alloc+0x1a/0x50 mm/mempolicy.c:2290
 filemap_alloc_folio+0xda/0x4f0 mm/filemap.c:971
 __filemap_get_folio+0x749/0xe80 mm/filemap.c:1965
 pagecache_get_page+0x28/0x250 mm/folio-compat.c:110
 find_or_create_page include/linux/pagemap.h:613 [inline]
 grow_dev_page fs/buffer.c:946 [inline]
 grow_buffers fs/buffer.c:1011 [inline]
 __getblk_slow fs/buffer.c:1038 [inline]
 __getblk_gfp+0x211/0xa20 fs/buffer.c:1333
 sb_getblk include/linux/buffer_head.h:356 [inline]
 get_empty_nodes+0x8c1/0xd70 fs/reiserfs/fix_node.c:890
 fix_nodes+0x2615/0x8c70 fs/reiserfs/fix_node.c:2662
 reiserfs_paste_into_item+0x65d/0x880 fs/reiserfs/stree.c:2130
 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_cont_expand_simple+0x187/0x2a0 fs/buffer.c:2347
 reiserfs_setattr+0x606/0x11c0 fs/reiserfs/inode.c:3305
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1440 [inline]
 free_pcp_prepare mm/page_alloc.c:1490 [inline]
 free_unref_page_prepare+0xf63/0x1120 mm/page_alloc.c:3358
 free_unref_page_list+0x663/0x900 mm/page_alloc.c:3499
 release_pages+0x2836/0x2b40 mm/swap.c:1055
 __pagevec_release+0x80/0xf0 mm/swap.c:1075
 pagevec_release include/linux/pagevec.h:71 [inline]
 folio_batch_release include/linux/pagevec.h:135 [inline]
 shmem_undo_range+0x867/0x2020 mm/shmem.c:946
 shmem_truncate_range mm/shmem.c:1045 [inline]
 shmem_evict_inode+0x265/0xa60 mm/shmem.c:1154
 evict+0x2a4/0x620 fs/inode.c:664
 __dentry_kill+0x436/0x650 fs/dcache.c:607
 dentry_kill+0xbb/0x290
 dput+0x21a/0x470 fs/dcache.c:913
 __fput+0x5e4/0x890 fs/file_table.c:328
 task_work_run+0x246/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:297
 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86

Memory state around the buggy address:
 ffff888060a26f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888060a26f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888060a27000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888060a27080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888060a27100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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