syzbot

EXT4-fs warning (device loop1): dx_probe:833: inode #2: comm syz.1.21: Unrecognised inode hash code 4
EXT4-fs warning (device loop1): dx_probe:966: inode #2: comm syz.1.21: Corrupt directory, running e2fsck is recommended
==================================================================
BUG: KASAN: use-after-free in __ext4_check_dir_entry+0x6fd/0x880 fs/ext4/dir.c:85
Read of size 2 at addr ffff8880320de003 by task syz.1.21/6041

CPU: 0 UID: 0 PID: 6041 Comm: syz.1.21 Not tainted 6.13.0-rc5-syzkaller-00161-g63676eefb7a0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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:378 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:489
 kasan_report+0x143/0x180 mm/kasan/report.c:602
 __ext4_check_dir_entry+0x6fd/0x880 fs/ext4/dir.c:85
 ext4_readdir+0x1436/0x3a60 fs/ext4/dir.c:259
 iterate_dir+0x571/0x800 fs/readdir.c:108
 __do_sys_getdents64 fs/readdir.c:403 [inline]
 __se_sys_getdents64+0x1e2/0x4b0 fs/readdir.c:389
 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: 0033:0x7f81cef85d29
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:00007ffd0fdd5d08 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 00007f81cf175fa0 RCX: 00007f81cef85d29
RDX: 0000000000000010 RSI: 0000000000000000 RDI: 0000000000000006
RBP: 00007f81cf001b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f81cf175fa0 R14: 00007f81cf175fa0 R15: 0000000000000175
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x320de
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0000c86108 ffffea0000c78688 0000000000000000
raw: 0000000000000000 0000000000000001 00000000f0000000 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 0xcc0(GFP_KERNEL), pid 2949, tgid 2949 (kworker/u8:7), ts 23682765784, free_ts 86494647811
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1f3/0x230 mm/page_alloc.c:1558
 prep_new_page mm/page_alloc.c:1566 [inline]
 get_page_from_freelist+0x3651/0x37a0 mm/page_alloc.c:3476
 __alloc_pages_noprof+0x292/0x710 mm/page_alloc.c:4753
 alloc_pages_mpol_noprof+0x3e8/0x680 mm/mempolicy.c:2269
 get_free_pages_noprof+0xc/0x30 mm/page_alloc.c:4800
 kasan_populate_vmalloc_pte+0x38/0xe0 mm/kasan/shadow.c:304
 apply_to_pte_range mm/memory.c:2831 [inline]
 apply_to_pmd_range mm/memory.c:2875 [inline]
 apply_to_pud_range mm/memory.c:2911 [inline]
 apply_to_p4d_range mm/memory.c:2947 [inline]
 __apply_to_page_range+0x806/0xde0 mm/memory.c:2981
 alloc_vmap_area+0x1d4e/0x2400 mm/vmalloc.c:2035
 __get_vm_area_node+0x1c8/0x2d0 mm/vmalloc.c:3137
 __vmalloc_node_range_noprof+0x344/0x1380 mm/vmalloc.c:3806
 alloc_thread_stack_node kernel/fork.c:314 [inline]
 dup_task_struct+0x444/0x8c0 kernel/fork.c:1116
 copy_process+0x5d1/0x3d50 kernel/fork.c:2224
 kernel_clone+0x223/0x870 kernel/fork.c:2806
 user_mode_thread+0x132/0x1a0 kernel/fork.c:2884
 call_usermodehelper_exec_work+0x5c/0x230 kernel/umh.c:171
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
page last free pid 25 tgid 25 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1127 [inline]
 free_unref_page+0xd2c/0x1000 mm/page_alloc.c:2659
 kasan_depopulate_vmalloc_pte+0x74/0x90 mm/kasan/shadow.c:408
 apply_to_pte_range mm/memory.c:2831 [inline]
 apply_to_pmd_range mm/memory.c:2875 [inline]
 apply_to_pud_range mm/memory.c:2911 [inline]
 apply_to_p4d_range mm/memory.c:2947 [inline]
 __apply_to_page_range+0x806/0xde0 mm/memory.c:2981
 kasan_release_vmalloc+0xa5/0xd0 mm/kasan/shadow.c:529
 kasan_release_vmalloc_node mm/vmalloc.c:2196 [inline]
 purge_vmap_node+0x22f/0x8d0 mm/vmalloc.c:2213
 __purge_vmap_area_lazy+0x708/0xae0 mm/vmalloc.c:2304
 drain_vmap_area_work+0x27/0x40 mm/vmalloc.c:2338
 process_one_work kernel/workqueue.c:3229 [inline]
 process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3310
 worker_thread+0x870/0xd30 kernel/workqueue.c:3391
 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:
 ffff8880320ddf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880320ddf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880320de000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff8880320de080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880320de100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================