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 tea 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 ffff88805b5b8fc4 by task syz.0.16/5044

CPU: 1 PID: 5044 Comm: syz.0.16 Not tainted 5.15.182-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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+0x1f65/0x23e0 fs/reiserfs/super.c:2178
 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:3013
 do_mount fs/namespace.c:3356 [inline]
 __do_sys_mount fs/namespace.c:3564 [inline]
 __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:3541
 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: 0033:0x7f4b34f3f90a
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:00007f4b341aee68 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f4b341aeef0 RCX: 00007f4b34f3f90a
RDX: 0000400000000180 RSI: 0000400000000040 RDI: 00007f4b341aeeb0
RBP: 0000400000000180 R08: 00007f4b341aeef0 R09: 000000000001801c
R10: 000000000001801c R11: 0000000000000246 R12: 0000400000000040
R13: 00007f4b341aeeb0 R14: 000000000000112d R15: 0000400000000300
 </TASK>

The buggy address belongs to the page:
page:ffffea00016d6e00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x5b5b8
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00016d6e48 ffffea00016d6dc8 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 0x8(__GFP_MOVABLE), pid 1, ts 18407893771, free_ts 19292985153
 split_map_pages+0x277/0x4c0 mm/compaction.c:99
 isolate_freepages_range+0x3dd/0x430 mm/compaction.c:749
 alloc_contig_range+0x97e/0xcd0 mm/page_alloc.c:9259
 __alloc_contig_pages mm/page_alloc.c:9283 [inline]
 alloc_contig_pages+0x390/0x490 mm/page_alloc.c:9363
 debug_vm_pgtable_alloc_huge_page+0xbf/0x110 mm/debug_vm_pgtable.c:1085
 init_args+0xb3a/0xdd0 mm/debug_vm_pgtable.c:1207
 debug_vm_pgtable+0x42/0x370 mm/debug_vm_pgtable.c:1245
 do_one_initcall+0x1ee/0x680 init/main.c:1302
 do_initcall_level+0x137/0x1f0 init/main.c:1375
 do_initcalls+0x4b/0x90 init/main.c:1391
 kernel_init_freeable+0x3ce/0x560 init/main.c:1615
 kernel_init+0x19/0x1b0 init/main.c:1506
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
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+0x94/0x280 mm/page_alloc.c:3396
 free_contig_range+0x96/0xf0 mm/page_alloc.c:9385
 destroy_args+0xef/0x8b0 mm/debug_vm_pgtable.c:1018
 debug_vm_pgtable+0x318/0x370 mm/debug_vm_pgtable.c:1331
 do_one_initcall+0x1ee/0x680 init/main.c:1302
 do_initcall_level+0x137/0x1f0 init/main.c:1375
 do_initcalls+0x4b/0x90 init/main.c:1391
 kernel_init_freeable+0x3ce/0x560 init/main.c:1615
 kernel_init+0x19/0x1b0 init/main.c:1506
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287

Memory state around the buggy address:
 ffff88805b5b8e80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805b5b8f00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88805b5b8f80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff88805b5b9000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88805b5b9080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================