==================================================================
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x7e3/0x990 fs/ext4/dir.c:85
Read of size 2 at addr ffff888128120003 by task syz.2.16/469

CPU: 1 PID: 469 Comm: syz.2.16 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 __dump_stack+0x21/0x30 lib/dump_stack.c:88
 dump_stack_lvl+0x110/0x170 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+0x10f/0x150 mm/kasan/report.c:444
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report_generic.c:307
 __ext4_check_dir_entry+0x7e3/0x990 fs/ext4/dir.c:85
 ext4_readdir+0x1205/0x3aa0 fs/ext4/dir.c:261
 iterate_dir+0x25c/0x600 fs/readdir.c:-1
 __do_sys_getdents64 fs/readdir.c:369 [inline]
 __se_sys_getdents64+0xf2/0x250 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: 0033:0x7f906c3df8f9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f906be47028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f906c60dfa0 RCX: 00007f906c3df8f9
RDX: 0000000000000010 RSI: 0000000000000000 RDI: 0000000000000005
RBP: 00007f906c4711bc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f906c60dfa0 R15: 00007ffe79abd4c8
 </TASK>

The buggy address belongs to the page:
page:ffffea0004a04800 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x128120
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004a04848 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 0x100cca(GFP_HIGHUSER_MOVABLE), pid 459, ts 44043079057, free_ts 44192967607
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x192/0x1b0 mm/page_alloc.c:2607
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2613
 get_page_from_freelist+0x2c3a/0x2cd0 mm/page_alloc.c:4487
 __alloc_pages+0x1a2/0x460 mm/page_alloc.c:5824
 __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_cow_fault mm/memory.c:4593 [inline]
 do_fault mm/memory.c:4711 [inline]
 handle_pte_fault+0xa72/0x2770 mm/memory.c:4923
 __handle_mm_fault mm/memory.c:-1 [inline]
 do_handle_mm_fault+0x1b3b/0x1e30 mm/memory.c:5345
 handle_mm_fault include/linux/mm.h:1847 [inline]
 do_user_addr_fault+0x808/0x11c0 arch/x86/mm/fault.c:1416
 handle_page_fault arch/x86/mm/fault.c:1507 [inline]
 exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1560
 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:1474 [inline]
 free_pcp_prepare mm/page_alloc.c:1546 [inline]
 free_unref_page_prepare+0x5fa/0x600 mm/page_alloc.c:3536
 free_unref_page_list+0x138/0x9e0 mm/page_alloc.c:3673
 release_pages+0x1264/0x12c0 mm/swap.c:1015
 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+0x17e/0x310 mm/mmu_gather.c:338
 exit_mmap+0x43b/0x8b0 mm/mmap.c:3248
 __mmput+0x92/0x300 kernel/fork.c:1191
 mmput+0x50/0x150 kernel/fork.c:1214
 exit_mm kernel/exit.c:561 [inline]
 do_exit+0xacc/0x29a0 kernel/exit.c:883
 do_group_exit+0x149/0x310 kernel/exit.c:1010
 get_signal+0x64f/0x1430 kernel/signal.c:2916
 arch_do_signal_or_restart+0xe2/0x1100 arch/x86/kernel/signal.c:867
 handle_signal_work kernel/entry/common.c:154 [inline]
 exit_to_user_mode_loop+0xa7/0xe0 kernel/entry/common.c:178
 exit_to_user_mode_prepare+0x87/0xd0 kernel/entry/common.c:214
 __syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:307
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:86

Memory state around the buggy address:
 ffff88812811ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88812811ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888128120000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888128120080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888128120100: 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.2.16: path (unknown): bad entry in directory: rec_len is smaller than minimal - offset=1023, inode=0, rec_len=0, size=1024 fake=0