EXT4-fs (loop2): mounted filesystem without journal. Opts: jqfmt=vfsold,data_err=abort,debug,noload,mblk_io_submit,commit=0x0000000000000005,init_itable=0x0000000000000601,max_dir_size_kb=0x0000000000000005,,errors=continue. Quota mode: none.
EXT4-fs warning (device loop2): dx_probe:833: inode #2: comm syz.2.21: Unrecognised inode hash code 4
EXT4-fs warning (device loop2): dx_probe:966: inode #2: comm syz.2.21: Corrupt directory, running e2fsck is recommended
EXT4-fs warning (device loop2): dx_probe:833: inode #2: comm syz.2.21: Unrecognised inode hash code 4
EXT4-fs warning (device loop2): dx_probe:966: inode #2: comm syz.2.21: Corrupt directory, running e2fsck is recommended
==================================================================
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x7c2/0x970 fs/ext4/dir.c:85
Read of size 2 at addr ffff8881243f0003 by task syz.2.21/488

CPU: 1 PID: 488 Comm: syz.2.21 Not tainted 5.15.189-syzkaller-1081280-gf32b52534f1d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x7f/0x2c0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0xf1/0x140 mm/kasan/report.c:444
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report_generic.c:307
 __ext4_check_dir_entry+0x7c2/0x970 fs/ext4/dir.c:85
 ext4_readdir+0x11c9/0x3a40 fs/ext4/dir.c:261
 iterate_dir+0x260/0x600 fs/readdir.c:-1
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0xe5/0x240 fs/readdir.c:354
 __x64_sys_getdents64+0x7b/0x90 fs/readdir.c:354
 x64_sys_call+0x592/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:218
 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: 0033:0x7f095c7fc929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f095c26d038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f095ca23fa0 RCX: 00007f095c7fc929
RDX: 0000000000000010 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007f095c87eb39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f095ca23fa0 R15: 00007ffeeb26ce88
 </TASK>

The buggy address belongs to the page:
page:ffffea000490fc00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x1243f0
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea000490fc48 ffff8881f713c580 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 0x100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 400, ts 55150526505, free_ts 55151243227
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2605
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2611
 get_page_from_freelist+0x2cc5/0x2d50 mm/page_alloc.c:4485
 __alloc_pages+0x18f/0x440 mm/page_alloc.c:5795
 __alloc_pages_node include/linux/gfp.h:595 [inline]
 alloc_pages_node include/linux/gfp.h:609 [inline]
 alloc_pages include/linux/gfp.h:622 [inline]
 do_anonymous_page mm/memory.c:4069 [inline]
 handle_pte_fault+0xe89/0x2680 mm/memory.c:4909
 __handle_mm_fault mm/memory.c:-1 [inline]
 do_handle_mm_fault+0x1a6d/0x1d50 mm/memory.c:5333
 handle_mm_fault include/linux/mm.h:1836 [inline]
 do_user_addr_fault+0x841/0x1180 arch/x86/mm/fault.c:1418
 handle_page_fault arch/x86/mm/fault.c:1509 [inline]
 exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1565
 asm_exc_page_fault+0x27/0x30 arch/x86/include/asm/idtentry.h:606
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1472 [inline]
 free_pcp_prepare mm/page_alloc.c:1544 [inline]
 free_unref_page_prepare+0x542/0x550 mm/page_alloc.c:3534
 free_unref_page_list+0x134/0x9d0 mm/page_alloc.c:3671
 release_pages+0xfda/0x1030 mm/swap.c:1014
 free_pages_and_swap_cache+0x86/0xa0 mm/swap_state.c:320
 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+0x175/0x300 mm/mmu_gather.c:338
 unmap_region+0x315/0x360 mm/mmap.c:2688
 __do_munmap+0xa0e/0xfe0 mm/mmap.c:2921
 __vm_munmap+0x15b/0x2a0 mm/mmap.c:2974
 __do_sys_munmap mm/mmap.c:3000 [inline]
 __se_sys_munmap mm/mmap.c:2996 [inline]
 __x64_sys_munmap+0x6b/0x80 mm/mmap.c:2996
 x64_sys_call+0xc9/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:12
 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:
 ffff8881243eff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8881243eff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8881243f0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8881243f0080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881243f0100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop2): ext4_readdir:263: inode #2: block 255: comm syz.2.21: path (unknown): bad entry in directory: rec_len % 4 != 0 - offset=1023, inode=4294967040, rec_len=65535, size=1024 fake=0