==================================================================
BUG: KASAN: use-after-free in dx_insert_block fs/ext4/namei.c:1387 [inline]
BUG: KASAN: use-after-free in do_split+0x1a78/0x1f70 fs/ext4/namei.c:2080
Read of size 157024 at addr ffff888123557028 by task syz.5.476/2762

CPU: 0 PID: 2762 Comm: syz.5.476 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
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x280/0x290 mm/kasan/generic.c:189
 memmove+0x2d/0x70 mm/kasan/shadow.c:54
 dx_insert_block fs/ext4/namei.c:1387 [inline]
 do_split+0x1a78/0x1f70 fs/ext4/namei.c:2080
 make_indexed_dir+0xe01/0x14a0 fs/ext4/namei.c:2392
 ext4_add_entry+0xc24/0xf40 fs/ext4/namei.c:2504
 __ext4_link+0x4d7/0x770 fs/ext4/namei.c:3536
 ext4_link+0x1de/0x270 fs/ext4/namei.c:3577
 vfs_link+0x636/0x7f0 fs/namei.c:4557
 do_linkat+0x1e7/0x730 fs/namei.c:4628
 __do_sys_link fs/namei.c:4662 [inline]
 __se_sys_link fs/namei.c:4660 [inline]
 __x64_sys_link+0x86/0x90 fs/namei.c:4660
 x64_sys_call+0x34d/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:87
 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: 0033:0x7f9e5a1e8de9
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:00007f9e59c5b038 EFLAGS: 00000246 ORIG_RAX: 0000000000000056
RAX: ffffffffffffffda RBX: 00007f9e5a401fa0 RCX: 00007f9e5a1e8de9
RDX: 0000000000000000 RSI: 0000400000000bc0 RDI: 0000400000001240
RBP: 00007f9e5a26a2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f9e5a401fa0 R15: 00007ffd3e36c878
 </TASK>

The buggy address belongs to the page:
page:ffffea00048d55c0 refcount:3 mapcount:1 mapping:ffff8881092cf258 index:0x1 pfn:0x123557
memcg:ffff888100256780
aops:def_blk_aops ino:700005
flags: 0x400000000032201e(referenced|uptodate|dirty|lru|private|mappedtodisk|unevictable|mlocked|zone=1)
raw: 400000000032201e ffffea0004b93ec8 ffffea0004372888 ffff8881092cf258
raw: 0000000000000001 ffff88811152c1f8 0000000300000000 ffff888100256780
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x108c48(GFP_NOFS|__GFP_NOFAIL|__GFP_HARDWALL|__GFP_MOVABLE), pid 2762, ts 196178895710, free_ts 196059543749
 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]
 __page_cache_alloc include/linux/pagemap.h:305 [inline]
 pagecache_get_page+0xa82/0xda0 mm/filemap.c:1954
 find_or_create_page include/linux/pagemap.h:418 [inline]
 grow_dev_page fs/buffer.c:949 [inline]
 grow_buffers fs/buffer.c:1014 [inline]
 __getblk_slow fs/buffer.c:1041 [inline]
 __getblk_gfp+0x238/0x7d0 fs/buffer.c:1336
 sb_getblk include/linux/buffer_head.h:361 [inline]
 ext4_getblk+0x210/0x630 fs/ext4/inode.c:878
 ext4_bread_batch+0x61/0x4c0 fs/ext4/inode.c:945
 __ext4_find_entry+0x1049/0x1bc0 fs/ext4/namei.c:1671
 ext4_lookup_entry fs/ext4/namei.c:1774 [inline]
 ext4_lookup+0x292/0x840 fs/ext4/namei.c:1842
 lookup_open fs/namei.c:3440 [inline]
 open_last_lookups fs/namei.c:3532 [inline]
 path_openat+0xfcf/0x2f10 fs/namei.c:3739
 do_filp_open+0x1b3/0x3e0 fs/namei.c:3769
 do_sys_openat2+0x14c/0x7b0 fs/open.c:1234
 do_sys_open fs/open.c:1250 [inline]
 __do_sys_creat fs/open.c:1326 [inline]
 __se_sys_creat fs/open.c:1320 [inline]
 __x64_sys_creat+0x8e/0xb0 fs/open.c:1320
 x64_sys_call+0x94a/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:86
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
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:
 ffff888123558f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888123558f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888123559000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888123559080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888123559100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
EXT4-fs error (device loop5): ext4_dx_csum_set:531: inode #2: comm syz.5.476: dir seems corrupt?  Run e2fsck -D.