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BUG: KASAN: use-after-free in reiserfs_release_objectid+0x521/0x780 fs/reiserfs/objectid.c:165
Read of size 8188 at addr ffff88805b736050 by task syz.6.431/6812

CPU: 1 PID: 6812 Comm: syz.6.431 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x27b/0x290 mm/kasan/generic.c:189
 memmove+0x25/0x60 mm/kasan/shadow.c:54
 reiserfs_release_objectid+0x521/0x780 fs/reiserfs/objectid.c:165
 remove_save_link+0x2b6/0x3c0 fs/reiserfs/super.c:542
 reiserfs_evict_inode+0x391/0x490 fs/reiserfs/inode.c:91
 evict+0x485/0x870 fs/inode.c:647
 __dentry_kill+0x431/0x650 fs/dcache.c:586
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xd8/0x1a0 fs/dcache.c:893
 __fput+0x5ee/0x930 fs/file_table.c:319
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x61e/0x20a0 kernel/exit.c:883
 do_group_exit+0x12e/0x300 kernel/exit.c:997
 get_signal+0x6ca/0x12c0 kernel/signal.c:2900
 arch_do_signal_or_restart+0xc1/0x1300 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x16/0x40 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f021bc3d749
Code: Unable to access opcode bytes at RIP 0x7f021bc3d71f.
RSP: 002b:00007f0219ea4038 EFLAGS: 00000246 ORIG_RAX: 0000000000000036
RAX: 0000000000000000 RBX: 00007f021be93fa0 RCX: 00007f021bc3d749
RDX: 0000000000000005 RSI: 0000000000000107 RDI: 0000000000000003
RBP: 00007f021bcc1f91 R08: 000000000000001c R09: 0000000000000000
R10: 0000200000000040 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f021be94038 R14: 00007f021be93fa0 R15: 00007ffd83f9d448
 </TASK>

The buggy address belongs to the page:
page:ffffea00016dcd80 refcount:2 mapcount:0 mapping:ffff888140902030 index:0x10 pfn:0x5b736
memcg:ffff88807d9e8000
aops:def_blk_aops ino:700006
flags: 0xfff00000022036(referenced|uptodate|lru|active|private|mappedtodisk|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000022036 ffffea00014bd848 ffffea000156e6c8 ffff888140902030
raw: 0000000000000010 ffff88807410a570 00000002ffffffff ffff88807d9e8000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x108c48(GFP_NOFS|__GFP_NOFAIL|__GFP_HARDWALL|__GFP_MOVABLE), pid 6813, ts 181617136065, free_ts 181578996080
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x1b77/0x1c60 mm/page_alloc.c:4192
 __alloc_pages+0x1e1/0x470 mm/page_alloc.c:5487
 __page_cache_alloc+0xd2/0x3f0 mm/filemap.c:1022
 pagecache_get_page+0x986/0xef0 mm/filemap.c:1940
 find_or_create_page include/linux/pagemap.h:420 [inline]
 grow_dev_page fs/buffer.c:949 [inline]
 grow_buffers fs/buffer.c:1014 [inline]
 __getblk_slow fs/buffer.c:1041 [inline]
 __getblk_gfp+0x249/0xb70 fs/buffer.c:1336
 __bread_gfp+0x28/0x380 fs/buffer.c:1381
 sb_bread include/linux/buffer_head.h:337 [inline]
 read_super_block+0x91/0x7a0 fs/reiserfs/super.c:1606
 reiserfs_fill_super+0x787/0x23e0 fs/reiserfs/super.c:1968
 mount_bdev+0x287/0x3c0 fs/super.c:1400
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x24a/0xa40 fs/namespace.c:3034
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3562
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
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+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page_list+0x122/0x7e0 mm/page_alloc.c:3433
 release_pages+0x184b/0x1bb0 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+0x164/0x2e0 mm/mmu_gather.c:338
 unmap_region+0x315/0x360 mm/mmap.c:2669
 __do_munmap+0x9d3/0xdc0 mm/mmap.c:2899
 __vm_munmap+0x137/0x230 mm/mmap.c:2952
 __do_sys_munmap mm/mmap.c:2978 [inline]
 __se_sys_munmap mm/mmap.c:2974 [inline]
 __x64_sys_munmap+0x67/0x70 mm/mmap.c:2974
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88805b736f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805b736f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805b737000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88805b737080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805b737100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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