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BUG: KASAN: use-after-free in strlen+0x53/0x60 lib/string.c:502
Read of size 1 at addr ffff888049e49008 by task syz-executor/4267

CPU: 1 PID: 4267 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x22e lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:316 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:420
 kasan_report+0x10b/0x140 mm/kasan/report.c:524
 strlen+0x53/0x60 lib/string.c:502
 __fortify_strlen include/linux/fortify-string.h:196 [inline]
 set_de_name_and_namelen fs/reiserfs/namei.c:82 [inline]
 search_by_entry_key+0xa84/0x1370 fs/reiserfs/namei.c:172
 reiserfs_readdir_inode+0x22c/0x1230 fs/reiserfs/dir.c:98
 iterate_dir+0x218/0x560 fs/readdir.c:-1
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0xe5/0x260 fs/readdir.c:354
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f9705bc20b3
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 62 3d f8 ff 66 90 b8 ff ff ff 7f 48 39 c2 48 0f 47 d0 b8 d9 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 05 c3 0f 1f 40 00 48 c7 c2 a8 ff ff ff f7 d8
RSP: 002b:00007ffe597067d8 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 0000555565563600 RCX: 00007f9705bc20b3
RDX: 0000000000008000 RSI: 0000555565563600 RDI: 0000000000000005
RBP: 00005555655635d4 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000001000 R11: 0000000000000293 R12: ffffffffffffffa8
R13: 0000000000000010 R14: 00005555655635d0 R15: 00007ffe59708a90
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001279240 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x49e49
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001279288 ffffea00012b6ec8 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 5810, tgid 5810 (dhcpcd-run-hook), ts 221831877845, free_ts 221889552923
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x173/0x1a0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x1a26/0x1ac0 mm/page_alloc.c:4328
 __alloc_pages+0x1df/0x4e0 mm/page_alloc.c:5614
 __folio_alloc+0xe/0x30 mm/page_alloc.c:5646
 vma_alloc_folio+0x4a3/0x900 mm/mempolicy.c:2243
 alloc_page_vma include/linux/gfp.h:284 [inline]
 wp_page_copy+0x26c/0x1640 mm/memory.c:3153
 handle_pte_fault mm/memory.c:5049 [inline]
 __handle_mm_fault mm/memory.c:5173 [inline]
 handle_mm_fault+0x1ca6/0x3e60 mm/memory.c:5294
 do_user_addr_fault+0x51f/0xb10 arch/x86/mm/fault.c:1340
 handle_page_fault arch/x86/mm/fault.c:1431 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1487
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:608
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1459 [inline]
 free_pcp_prepare mm/page_alloc.c:1509 [inline]
 free_unref_page_prepare+0x8b4/0x9a0 mm/page_alloc.c:3384
 free_unref_page_list+0xbb/0x8e0 mm/page_alloc.c:3525
 release_pages+0x1f92/0x2200 mm/swap.c:1035
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
 tlb_flush_mmu+0xff/0x210 mm/mmu_gather.c:261
 tlb_finish_mmu+0xbd/0x1c0 mm/mmu_gather.c:361
 exit_mmap+0x343/0x8e0 mm/mmap.c:3262
 __mmput+0x118/0x3c0 kernel/fork.c:1200
 exit_mm+0x1e6/0x2c0 kernel/exit.c:565
 do_exit+0x8c1/0x2400 kernel/exit.c:867
 do_group_exit+0x217/0x2d0 kernel/exit.c:1022
 __do_sys_exit_group kernel/exit.c:1033 [inline]
 __se_sys_exit_group kernel/exit.c:1031 [inline]
 __x64_sys_exit_group+0x3b/0x40 kernel/exit.c:1031
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2

Memory state around the buggy address:
 ffff888049e48f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888049e48f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888049e49000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                      ^
 ffff888049e49080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888049e49100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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