EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
EXT4-fs warning (device loop1): dx_probe:801: inode #2: comm syz.1.17: Unrecognised inode hash code 4
EXT4-fs warning (device loop1): dx_probe:934: inode #2: comm syz.1.17: Corrupt directory, running e2fsck is recommended
==================================================================
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x708/0x8a0 fs/ext4/dir.c:85
Read of size 2 at addr ffff88803f4bb003 by task syz.1.17/6452

CPU: 1 UID: 0 PID: 6452 Comm: syz.1.17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 __ext4_check_dir_entry+0x708/0x8a0 fs/ext4/dir.c:85
 ext4_readdir+0x12a2/0x3b70 fs/ext4/dir.c:262
 iterate_dir+0x3a5/0x580 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:410 [inline]
 __se_sys_getdents64+0xe4/0x260 fs/readdir.c:396
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbd8213e929
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:00007fbd813ae038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007fbd82365fa0 RCX: 00007fbd8213e929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007fbd821c0b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fbd82365fa0 R15: 00007ffd7123b7a8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff88803f4bb180 pfn:0x3f4bb
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 ffff8880b8942060 ffff8880b8942060 0000000000000000
raw: ffff88803f4bb180 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 6155, tgid 6155 (syz-executor), ts 140770600938, free_ts 143193075963
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1851
 prep_new_page mm/page_alloc.c:1859 [inline]
 get_page_from_freelist+0x2119/0x21b0 mm/page_alloc.c:3858
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5148
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2416
 alloc_frozen_pages_noprof mm/mempolicy.c:2487 [inline]
 alloc_pages_noprof+0xcf/0x1e0 mm/mempolicy.c:2507
 vm_area_alloc_pages mm/vmalloc.c:3642 [inline]
 __vmalloc_area_node mm/vmalloc.c:3720 [inline]
 __vmalloc_node_range_noprof+0x97d/0x12f0 mm/vmalloc.c:3893
 vmalloc_user_noprof+0xad/0xf0 mm/vmalloc.c:4046
 kcov_ioctl+0x58/0x650 kernel/kcov.c:716
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:598 [inline]
 __se_sys_ioctl+0xff/0x170 fs/ioctl.c:584
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 6173 tgid 6173 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 __free_frozen_pages+0xb59/0xce0 mm/page_alloc.c:2895
 vfree+0x2ad/0x470 mm/vmalloc.c:3434
 kcov_put kernel/kcov.c:439 [inline]
 kcov_close+0x2e/0x60 kernel/kcov.c:535
 __fput+0x458/0xa80 fs/file_table.c:468
 task_work_run+0x1d4/0x260 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x6b5/0x2300 kernel/exit.c:961
 do_group_exit+0x21c/0x2d0 kernel/exit.c:1102
 get_signal+0x125e/0x1310 kernel/signal.c:3034
 arch_do_signal_or_restart+0x9a/0x750 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop+0x75/0x110 kernel/entry/common.c:40
 exit_to_user_mode_prepare include/linux/irq-entry-common.h:225 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:175 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:210 [inline]
 do_syscall_64+0x2bd/0x3b0 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88803f4baf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88803f4baf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88803f4bb000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88803f4bb080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803f4bb100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================