loop0: detected capacity change from 0 to 512
[EXT4 FS bs=1024, gc=1, bpg=8192, ipg=32, mo=a85ec098, mo2=0002]
System zones: 1-12
EXT4-fs error (device loop0): __ext4_iget:4984: inode #15: block 1803188595: comm syz.0.0: invalid block
EXT4-fs error (device loop0): ext4_orphan_get:1394: comm syz.0.0: couldn't read orphan inode 15 (err -117)
EXT4-fs (loop0): mounted filesystem 00000007-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
==================================================================
BUG: KASAN: slab-use-after-free in ext4_insert_dentry+0x36a/0x6d0 fs/ext4/namei.c:2119
Write of size 251 at addr ffff888043431f14 by task syz.0.0/5329

CPU: 0 UID: 0 PID: 5329 Comm: syz.0.0 Not tainted 6.12.0-syzkaller-07749-g28eb75e178d3 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
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:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 __asan_memcpy+0x40/0x70 mm/kasan/shadow.c:106
 ext4_insert_dentry+0x36a/0x6d0 fs/ext4/namei.c:2119
 add_dirent_to_buf+0x3d9/0x750 fs/ext4/namei.c:2164
 make_indexed_dir+0xf98/0x1600 fs/ext4/namei.c:2361
 ext4_add_entry+0xcf7/0xfa0 fs/ext4/namei.c:2462
 ext4_add_nondir+0x8d/0x290 fs/ext4/namei.c:2803
 ext4_symlink+0x920/0xb50 fs/ext4/namei.c:3438
 vfs_symlink+0x137/0x2e0 fs/namei.c:4669
 do_symlinkat+0x222/0x3a0 fs/namei.c:4695
 __do_sys_symlink fs/namei.c:4716 [inline]
 __se_sys_symlink fs/namei.c:4714 [inline]
 __x64_sys_symlink+0x7a/0x90 fs/namei.c:4714
 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: 0033:0x7fd9a877e819
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:00007fd9a95a0038 EFLAGS: 00000246 ORIG_RAX: 0000000000000058
RAX: ffffffffffffffda RBX: 00007fd9a8935fa0 RCX: 00007fd9a877e819
RDX: 0000000000000000 RSI: 0000000020000cc0 RDI: 0000000020000dc0
RBP: 00007fd9a87f175e R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fd9a8935fa0 R15: 00007ffdf99defb8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:3 mapcount:0 mapping:ffff8880004a4d78 index:0x3f pfn:0x43431
memcg:ffff8880312be000
aops:def_blk_aops ino:700000 dentry name(?):""
flags: 0x4fff08000004214(referenced|dirty|workingset|private|node=1|zone=1|lastcpupid=0x7ff)
raw: 04fff08000004214 0000000000000000 dead000000000122 ffff8880004a4d78
raw: 000000000000003f ffff888042fa1570 00000003ffffffff ffff8880312be000
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 5329, tgid 5328 (syz.0.0), ts 72345174420, free_ts 72337848567
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1556
 prep_new_page mm/page_alloc.c:1564 [inline]
 get_page_from_freelist+0x3649/0x3790 mm/page_alloc.c:3474
 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4751
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2265
 alloc_pages_noprof mm/mempolicy.c:2345 [inline]
 folio_alloc_noprof+0x128/0x180 mm/mempolicy.c:2352
 filemap_alloc_folio_noprof+0xdf/0x500 mm/filemap.c:1010
 __filemap_get_folio+0x446/0xbd0 mm/filemap.c:1952
 grow_dev_folio fs/buffer.c:1042 [inline]
 grow_buffers fs/buffer.c:1108 [inline]
 __getblk_slow fs/buffer.c:1134 [inline]
 bdev_getblk+0x1d8/0x550 fs/buffer.c:1436
 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+0x523/0x1600 fs/ext4/namei.c:2282
 ext4_add_entry+0xcf7/0xfa0 fs/ext4/namei.c:2462
 ext4_add_nondir+0x8d/0x290 fs/ext4/namei.c:2803
 ext4_symlink+0x920/0xb50 fs/ext4/namei.c:3438
 vfs_symlink+0x137/0x2e0 fs/namei.c:4669
page last free pid 16 tgid 16 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0xdf9/0x1140 mm/page_alloc.c:2657
 rcu_do_batch kernel/rcu/tree.c:2567 [inline]
 rcu_core+0xaaa/0x17a0 kernel/rcu/tree.c:2823
 handle_softirqs+0x2c5/0x980 kernel/softirq.c:554
 run_ksoftirqd+0xca/0x130 kernel/softirq.c:943
 smpboot_thread_fn+0x544/0xa30 kernel/smpboot.c:164
 kthread+0x2f0/0x390 kernel/kthread.c:389
 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

Memory state around the buggy address:
 ffff888043431f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888043431f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888043432000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888043432080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
 ffff888043432100: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb
==================================================================