REISERFS (device loop0): using ordered data mode
reiserfs: using flush barriers
REISERFS (device loop0): journal params: device loop0, size 512, journal first block 18, max trans len 256, max batch 225, max commit age 30, max trans age 30
REISERFS (device loop0): checking transaction log (loop0)
REISERFS (device loop0): Using r5 hash to sort names
==================================================================
BUG: KASAN: use-after-free in bin_search_in_dir_item fs/reiserfs/namei.c:40 [inline]
BUG: KASAN: use-after-free in search_by_entry_key+0x597/0x1370 fs/reiserfs/namei.c:165
Read of size 4 at addr ffff8880618ee754 by task syz.0.16/5080

CPU: 1 PID: 5080 Comm: syz.0.16 Not tainted 5.15.189-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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
 bin_search_in_dir_item fs/reiserfs/namei.c:40 [inline]
 search_by_entry_key+0x597/0x1370 fs/reiserfs/namei.c:165
 reiserfs_find_entry+0x2ff/0x18e0 fs/reiserfs/namei.c:322
 reiserfs_lookup+0x1a7/0x420 fs/reiserfs/namei.c:368
 __lookup_slow+0x27d/0x3d0 fs/namei.c:1663
 lookup_one_len+0x18e/0x2c0 fs/namei.c:2718
 reiserfs_lookup_privroot+0x85/0x1e0 fs/reiserfs/xattr.c:980
 reiserfs_fill_super+0x1760/0x23e0 fs/reiserfs/super.c:2196
 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:3014
 do_mount fs/namespace.c:3357 [inline]
 __do_sys_mount fs/namespace.c:3565 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3542
 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
RIP: 0033:0x7f541951990a
Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb a6 e8 de 1a 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 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:00007f5418788e68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f5418788ef0 RCX: 00007f541951990a
RDX: 0000200000000000 RSI: 0000200000000440 RDI: 00007f5418788eb0
RBP: 0000200000000000 R08: 00007f5418788ef0 R09: 000000000120c081
R10: 000000000120c081 R11: 0000000000000246 R12: 0000200000000440
R13: 00007f5418788eb0 R14: 0000000000001108 R15: 0000200000000900
 </TASK>

The buggy address belongs to the page:
page:ffffea0001863b80 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x618ee
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001863bc8 ffff8880b9140960 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 4591, ts 83359190246, free_ts 86174301748
 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:5474
 alloc_pages_vma+0x393/0x7c0 mm/mempolicy.c:2146
 do_anonymous_page mm/memory.c:3838 [inline]
 handle_pte_fault mm/memory.c:4648 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x2382/0x43c0 mm/memory.c:4883
 do_user_addr_fault+0x489/0xc80 arch/x86/mm/fault.c:1357
 handle_page_fault arch/x86/mm/fault.c:1445 [inline]
 exc_page_fault+0x60/0x100 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+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:2665
 __do_munmap+0x9d3/0xdc0 mm/mmap.c:2895
 __vm_munmap+0x137/0x230 mm/mmap.c:2948
 __do_sys_munmap mm/mmap.c:2974 [inline]
 __se_sys_munmap mm/mmap.c:2970 [inline]
 __x64_sys_munmap+0x67/0x70 mm/mmap.c:2970
 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:
 ffff8880618ee600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880618ee680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880618ee700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                 ^
 ffff8880618ee780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880618ee800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================