EXT4-fs warning (device loop2): dx_probe:833: inode #2: comm syz.2.18: Unrecognised inode hash code 4
EXT4-fs warning (device loop2): dx_probe:966: inode #2: comm syz.2.18: Corrupt directory, running e2fsck is recommended
==================================================================
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x79c/0x930 fs/ext4/dir.c:85
Read of size 2 at addr ffff88812909c003 by task syz.2.18/487

CPU: 1 PID: 487 Comm: syz.2.18 Not tainted 5.15.180-syzkaller-1080019-g8034ec1338e8 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1c0 lib/dump_stack.c:106
 print_address_description+0x87/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:444
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report_generic.c:307
 __ext4_check_dir_entry+0x79c/0x930 fs/ext4/dir.c:85
 ext4_readdir+0x1486/0x40f0 fs/ext4/dir.c:261
 iterate_dir+0x265/0x600 fs/readdir.c:-1
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0x1c1/0x460 fs/readdir.c:354
 __x64_sys_getdents64+0x7b/0x90 fs/readdir.c:354
 x64_sys_call+0x5ae/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:218
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f8cc6126169
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:00007f8cc5b98038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f8cc633efa0 RCX: 00007f8cc6126169
RDX: 0000000000000010 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f8cc61a72a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f8cc633efa0 R15: 00007fffa99e2478
 </TASK>

The buggy address belongs to the page:
page:ffffea0004a42700 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x12909c
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004a42748 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 487, ts 54260271500, free_ts 54262087294
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2605
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2611
 get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4485
 __alloc_pages+0x27e/0x8f0 mm/page_alloc.c:5781
 __alloc_pages_node include/linux/gfp.h:591 [inline]
 alloc_pages_node include/linux/gfp.h:605 [inline]
 alloc_pages include/linux/gfp.h:618 [inline]
 wp_page_copy+0x1d4/0x1b00 mm/memory.c:3220
 do_wp_page+0x9ca/0xc90 mm/memory.c:-1
 handle_pte_fault+0x7f1/0x28f0 mm/memory.c:4931
 __handle_mm_fault mm/memory.c:-1 [inline]
 do_handle_mm_fault+0x20bc/0x2400 mm/memory.c:5332
 do_user_addr_fault arch/x86/mm/fault.c:1325 [inline]
 handle_page_fault arch/x86/mm/fault.c:1509 [inline]
 exc_page_fault+0x26f/0x7f0 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+0x7c8/0x7d0 mm/page_alloc.c:3534
 free_unref_page_list+0x14b/0xa60 mm/page_alloc.c:3671
 release_pages+0x1310/0x1370 mm/swap.c:1009
 free_pages_and_swap_cache+0x8a/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+0x177/0x320 mm/mmu_gather.c:338
 unmap_region+0x304/0x350 mm/mmap.c:2680
 __do_munmap+0x13e4/0x19d0 mm/mmap.c:2913
 __vm_munmap+0x166/0x2a0 mm/mmap.c:2966
 __do_sys_munmap mm/mmap.c:2992 [inline]
 __se_sys_munmap mm/mmap.c:2988 [inline]
 __x64_sys_munmap+0x6b/0x80 mm/mmap.c:2988
 x64_sys_call+0x75/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:12
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0x80 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0

Memory state around the buggy address:
 ffff88812909bf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88812909bf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88812909c000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88812909c080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812909c100: 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.2.18: path (unknown): bad entry in directory: rec_len is smaller than minimal - offset=1023, inode=0, rec_len=0, size=1024 fake=0