EXT4-fs (loop0): mounted filesystem 00000007-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_insert_dentry+0x3cd/0x780 fs/ext4/namei.c:2119
Write of size 251 at addr ffff888079153f14 by task syz.0.16/6758

CPU: 0 UID: 0 PID: 6758 Comm: syz.0.16 Not tainted 6.14.0-rc7-syzkaller-00069-g81e4f8d68c66 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0x16e/0x5b0 mm/kasan/report.c:521
 kasan_report+0x143/0x180 mm/kasan/report.c:634
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 ext4_insert_dentry+0x3cd/0x780 fs/ext4/namei.c:2119
 add_dirent_to_buf+0x315/0x660 fs/ext4/namei.c:2164
 make_indexed_dir+0xcaf/0x1280 fs/ext4/namei.c:2361
 ext4_add_entry+0xb36/0xd30 fs/ext4/namei.c:2462
 ext4_add_nondir+0x8d/0x290 fs/ext4/namei.c:2803
 ext4_symlink+0xa10/0xda0 fs/ext4/namei.c:3440
 vfs_symlink+0x137/0x2e0 fs/namei.c:4671
 do_symlinkat+0x222/0x3a0 fs/namei.c:4697
 __do_sys_symlink fs/namei.c:4718 [inline]
 __se_sys_symlink fs/namei.c:4716 [inline]
 __x64_sys_symlink+0x7a/0x90 fs/namei.c:4716
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1e2518d169
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:00007f1e25fe9038 EFLAGS: 00000246 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 00007f1e253a5fa0 RCX: 00007f1e2518d169
RDX: 0000000000000000 RSI: 0000400000000cc0 RDI: 0000400000000dc0
RBP: 00007f1e2520e2a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f1e253a5fa0 R15: 00007ffe1325cfd8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:3 mapcount:0 mapping:ffff888023883678 index:0x3f pfn:0x79153
memcg:ffff888065214000
aops:def_blk_aops ino:700000 dentry name(?):""
flags: 0xfff00000004114(referenced|dirty|active|private|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000004114 0000000000000000 dead000000000122 ffff888023883678
raw: 000000000000003f ffff888078652488 00000003ffffffff ffff888065214000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x148c40(GFP_NOFS|__GFP_NOFAIL|__GFP_COMP|__GFP_HARDWALL), pid 6758, tgid 6757 (syz.0.16), ts 115758308828, free_ts 115754839215
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f4/0x240 mm/page_alloc.c:1551
 prep_new_page mm/page_alloc.c:1559 [inline]
 get_page_from_freelist+0x3651/0x37a0 mm/page_alloc.c:3477
 __alloc_frozen_pages_noprof+0x292/0x710 mm/page_alloc.c:4740
 alloc_pages_mpol+0x311/0x660 mm/mempolicy.c:2270
 alloc_frozen_pages_noprof mm/mempolicy.c:2341 [inline]
 alloc_pages_noprof+0x121/0x190 mm/mempolicy.c:2361
 folio_alloc_noprof+0x1e/0x30 mm/mempolicy.c:2371
 filemap_alloc_folio_noprof+0xe1/0x540 mm/filemap.c:1018
 __filemap_get_folio+0x423/0xb40 mm/filemap.c:1969
 grow_dev_folio fs/buffer.c:1039 [inline]
 grow_buffers fs/buffer.c:1105 [inline]
 __getblk_slow fs/buffer.c:1131 [inline]
 bdev_getblk+0x1d4/0x670 fs/buffer.c:1431
 getblk_unmovable include/linux/buffer_head.h:369 [inline]
 ext4_getblk+0x31b/0x880 fs/ext4/inode.c:864
 ext4_bread+0x2e/0x180 fs/ext4/inode.c:912
 ext4_append+0x327/0x5c0 fs/ext4/namei.c:83
 make_indexed_dir+0x3ff/0x1280 fs/ext4/namei.c:2282
 ext4_add_entry+0xb36/0xd30 fs/ext4/namei.c:2462
 ext4_add_nondir+0x8d/0x290 fs/ext4/namei.c:2803
 ext4_symlink+0xa10/0xda0 fs/ext4/namei.c:3440
page last free pid 6767 tgid 6767 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_frozen_pages+0xe04/0x10e0 mm/page_alloc.c:2660
 tlb_batch_list_free mm/mmu_gather.c:159 [inline]
 tlb_finish_mmu+0x11f/0x200 mm/mmu_gather.c:491
 exit_mmap+0x52a/0xd40 mm/mmap.c:1297
 __mmput+0x115/0x410 kernel/fork.c:1356
 exit_mm+0x220/0x310 kernel/exit.c:570
 do_exit+0x9ad/0x2940 kernel/exit.c:925
 do_group_exit+0x207/0x2c0 kernel/exit.c:1087
 __do_sys_exit_group kernel/exit.c:1098 [inline]
 __se_sys_exit_group kernel/exit.c:1096 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1096
 x64_sys_call+0x26a8/0x26b0 arch/x86/include/generated/asm/syscalls_64.h:232
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888079153f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888079153f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888079154000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888079154080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888079154100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================