EXT4-fs (loop2): 1 truncate cleaned up
EXT4-fs (loop2): mounted filesystem without journal. Quota mode: none.
EXT4-fs warning (device loop2): __ext4fs_dirhash:270: inode #2: comm syz.2.24: Siphash requires key
EXT4-fs warning (device loop2): dx_probe:845: inode #2: comm syz.2.24: Hash code is SIPHASH, but hash not in dirent
EXT4-fs warning (device loop2): dx_probe:966: inode #2: comm syz.2.24: 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 ffff888124e62003 by task syz.2.24/569

CPU: 0 PID: 569 Comm: syz.2.24 Not tainted 6.1.141-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack+0x21/0x24 lib/dump_stack.c:88
 dump_stack_lvl+0xee/0x150 lib/dump_stack.c:106
 print_address_description+0x71/0x210 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:427
 kasan_report+0x122/0x150 mm/kasan/report.c:531
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report_generic.c:349
 __ext4_check_dir_entry+0x7c2/0x970 fs/ext4/dir.c:85
 ext4_readdir+0x1266/0x3c10 fs/ext4/dir.c:261
 iterate_dir+0x271/0x610 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+0x15c/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:218
 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: 0033:0x7f44ce18e929
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:00007f44cf011038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f44ce3b5fa0 RCX: 00007f44ce18e929
RDX: 0000000000000010 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f44ce210b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f44ce3b5fa0 R15: 00007ffe890ca028
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0004939880 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x124e62
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004984b48 ffffea0004939a08 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 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_COMP|__GFP_ZERO), pid 565, tgid 565 (syz.2.23), ts 53333949471, free_ts 53437176550
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1d0/0x1f0 mm/page_alloc.c:2532
 prep_new_page mm/page_alloc.c:2539 [inline]
 get_page_from_freelist+0x2e63/0x2ef0 mm/page_alloc.c:4328
 __alloc_pages+0x235/0x4b0 mm/page_alloc.c:5614
 __folio_alloc+0x12/0x40 mm/page_alloc.c:5646
 __folio_alloc_node include/linux/gfp.h:246 [inline]
 folio_alloc include/linux/gfp.h:275 [inline]
 alloc_page_vma include/linux/gfp.h:284 [inline]
 do_anonymous_page mm/memory.c:4191 [inline]
 handle_pte_fault mm/memory.c:5029 [inline]
 __handle_mm_fault mm/memory.c:5173 [inline]
 handle_mm_fault+0x17b4/0x23d0 mm/memory.c:5294
 do_user_addr_fault+0x530/0xaf0 arch/x86/mm/fault.c:1340
 handle_page_fault arch/x86/mm/fault.c:1431 [inline]
 exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1487
 asm_exc_page_fault+0x27/0x30 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:1532 [inline]
 free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3384
 free_unref_page_list+0xba/0x7c0 mm/page_alloc.c:3525
 release_pages+0xad1/0xb20 mm/swap.c:1035
 free_pages_and_swap_cache+0x86/0xa0 mm/swap_state.c:314
 tlb_batch_pages_flush mm/mmu_gather.c:59 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:254 [inline]
 tlb_flush_mmu mm/mmu_gather.c:261 [inline]
 tlb_finish_mmu+0x1aa/0x370 mm/mmu_gather.c:361
 exit_mmap+0x31f/0x750 mm/mmap.c:3250
 __mmput+0x93/0x320 kernel/fork.c:1200
 mmput+0x47/0x60 kernel/fork.c:1222
 exit_mm kernel/exit.c:565 [inline]
 do_exit+0x957/0x2410 kernel/exit.c:858
 do_group_exit+0x210/0x2d0 kernel/exit.c:1021
 __do_sys_exit_group kernel/exit.c:1032 [inline]
 __se_sys_exit_group kernel/exit.c:1030 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1030
 x64_sys_call+0x7b4/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:232
 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:
 ffff888124e61f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888124e61f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888124e62000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888124e62080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888124e62100: 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.2.24: path (unknown): bad entry in directory: rec_len % 4 != 0 - offset=1023, inode=554383616, rec_len=17614, size=1024 fake=0