==================================================================
BUG: KASAN: use-after-free in ext4_htree_fill_tree+0x1066/0x10d0 fs/ext4/namei.c:1246
Read of size 1 at addr ffff88812861cd1b by task syz-executor/471

CPU: 1 PID: 471 Comm: syz-executor Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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+0x71/0x1e0 mm/kasan/report.c:316
 print_report+0x4a/0x60 mm/kasan/report.c:418
 kasan_report+0x122/0x150 mm/kasan/report.c:522
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report_generic.c:348
 ext4_htree_fill_tree+0x1066/0x10d0 fs/ext4/namei.c:1246
 ext4_dx_readdir fs/ext4/dir.c:608 [inline]
 ext4_readdir+0x2d8a/0x3c10 fs/ext4/dir.c:145
 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: 0033:0x7f85a2fb8693
Code: c1 66 0f 1f 44 00 00 48 83 c4 08 48 89 ef 5b 5d e9 82 3e 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:00007ffc8a1254e8 EFLAGS: 00000293 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00005555817cd4e0 RCX: 00007f85a2fb8693
RDX: 0000000000008000 RSI: 00005555817cd4e0 RDI: 0000000000000005
RBP: 00005555817cd4b4 R08: 0000000000028b61 R09: 0000000000000000
R10: 00007f85a314bca0 R11: 0000000000000293 R12: ffffffffffffffa8
R13: 0000000000000010 R14: 00005555817cd4b0 R15: 0000000000000001
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0004a18700 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x12861c
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 ffffea0004a18748 ffffea0004a186c8 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 446, tgid 446 (syz-executor), ts 47562947852, free_ts 48065404991
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1f5/0x210 mm/page_alloc.c:2643
 prep_new_page+0x1c/0x110 mm/page_alloc.c:2650
 get_page_from_freelist+0x2c7b/0x2cf0 mm/page_alloc.c:4554
 __alloc_pages+0x1c3/0x450 mm/page_alloc.c:5868
 __folio_alloc+0x12/0x40 mm/page_alloc.c:5900
 __folio_alloc_node include/linux/gfp.h:245 [inline]
 folio_alloc include/linux/gfp.h:274 [inline]
 alloc_page_vma include/linux/gfp.h:283 [inline]
 do_cow_fault mm/memory.c:4761 [inline]
 do_fault+0x4c0/0x1df0 mm/memory.c:4877
 handle_pte_fault mm/memory.c:5171 [inline]
 __handle_mm_fault mm/memory.c:5313 [inline]
 handle_mm_fault+0x12fa/0x2640 mm/memory.c:5453
 do_user_addr_fault+0x905/0x1050 arch/x86/mm/fault.c:1323
 handle_page_fault arch/x86/mm/fault.c:1466 [inline]
 exc_page_fault+0x51/0xb0 arch/x86/mm/fault.c:1522
 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:26 [inline]
 free_pages_prepare mm/page_alloc.c:1551 [inline]
 free_pcp_prepare mm/page_alloc.c:1625 [inline]
 free_unref_page_prepare+0x742/0x750 mm/page_alloc.c:3589
 free_unref_page_list+0x112/0x8b0 mm/page_alloc.c:3740
 release_pages+0xad1/0xb20 mm/swap.c:1043
 free_pages_and_swap_cache+0x86/0xa0 mm/swap_state.c:315
 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+0x3dd/0xb60 mm/mmap.c:3378
 __mmput+0x93/0x320 kernel/fork.c:1300
 mmput+0x4b/0x150 kernel/fork.c:1323
 exit_mm kernel/exit.c:568 [inline]
 do_exit+0x981/0x2650 kernel/exit.c:873
 do_group_exit+0x210/0x2d0 kernel/exit.c:1028
 get_signal+0x13b5/0x1520 kernel/signal.c:2889
 arch_do_signal_or_restart+0xb0/0x1030 arch/x86/kernel/signal.c:871
 exit_to_user_mode_loop+0x7a/0xb0 kernel/entry/common.c:174
 exit_to_user_mode_prepare+0x5a/0xa0 kernel/entry/common.c:210
 __syscall_exit_to_user_mode_work kernel/entry/common.c:292 [inline]
 syscall_exit_to_user_mode+0x1a/0x30 kernel/entry/common.c:303
 do_syscall_64+0x58/0xa0 arch/x86/entry/common.c:87

Memory state around the buggy address:
 ffff88812861cc00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812861cc80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88812861cd00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88812861cd80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88812861ce00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop2): __ext4_get_inode_loc:4509: comm syz-executor: Invalid inode table block 14875662660405297151 in block_group 0
EXT4-fs error (device loop2) in ext4_reserve_inode_write:5917: Corrupt filesystem
EXT4-fs error (device loop2): ext4_dirty_inode:6121: inode #2: comm syz-executor: mark_inode_dirty error
EXT4-fs (loop2): unmounting filesystem.