hpfs: code page support is disabled
HPFS: de_next_de: de->length = 84ba
HPFS: dnode_end_de: dnode->first_free = 7b3184b6
==================================================================
BUG: KASAN: use-after-free in hpfs_count_dnodes+0x874/0xb70 fs/hpfs/dnode.c:773
Read of size 2 at addr ffff888057abd4d0 by task syz.1.18/6632

CPU: 1 UID: 0 PID: 6632 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xba/0x230 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 hpfs_count_dnodes+0x874/0xb70 fs/hpfs/dnode.c:773
 hpfs_read_inode+0xc79/0x1050 fs/hpfs/inode.c:128
 hpfs_fill_super+0x123d/0x1fa0 fs/hpfs/super.c:651
 get_tree_bdev_flags+0x431/0x4f0 fs/super.c:1694
 vfs_get_tree+0x92/0x2a0 fs/super.c:1754
 fc_mount fs/namespace.c:1193 [inline]
 do_new_mount_fc fs/namespace.c:3760 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3836
 do_mount fs/namespace.c:4159 [inline]
 __do_sys_mount fs/namespace.c:4348 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4325
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1845b2b90a
Code: 48 c7 c2 e8 ff ff ff f7 d8 64 89 02 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f184518de58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f184518dee0 RCX: 00007f1845b2b90a
RDX: 000020000000a000 RSI: 0000200000009ec0 RDI: 00007f184518dea0
RBP: 000020000000a000 R08: 00007f184518dee0 R09: 0000000003200041
R10: 0000000003200041 R11: 0000000000000246 R12: 0000200000009ec0
R13: 00007f184518dea0 R14: 0000000000009e21 R15: 0000200000000000
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x7f183cd7b pfn:0x57abd
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 ffffea00015eaf08 ffffea00015eaf88 0000000000000000
raw: 00000007f183cd7b 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO|__GFP_COMP), pid 6632, tgid 6631 (syz.1.18), ts 152934751513, free_ts 153011403669
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1889
 prep_new_page mm/page_alloc.c:1897 [inline]
 get_page_from_freelist+0x28bb/0x2950 mm/page_alloc.c:3962
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5250
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2484
 folio_alloc_mpol_noprof mm/mempolicy.c:2503 [inline]
 vma_alloc_folio_noprof+0xea/0x290 mm/mempolicy.c:2538
 folio_prealloc mm/memory.c:-1 [inline]
 alloc_anon_folio mm/memory.c:5208 [inline]
 do_anonymous_page mm/memory.c:5265 [inline]
 do_pte_missing+0x810/0x2d30 mm/memory.c:4475
 handle_pte_fault mm/memory.c:6316 [inline]
 __handle_mm_fault mm/memory.c:6454 [inline]
 handle_mm_fault+0xd0a/0x13c0 mm/memory.c:6623
 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618
page last free pid 6535 tgid 6535 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1433 [inline]
 free_unref_folios+0xe7b/0x1c70 mm/page_alloc.c:3040
 folios_put_refs+0x56f/0x680 mm/swap.c:1002
 folios_put include/linux/mm.h:1876 [inline]
 folio_batch_move_lru+0x2a6/0x340 mm/swap.c:179
 __folio_batch_add_and_move+0x446/0xa90 mm/swap.c:196
 filemap_add_folio+0x3cf/0x610 mm/filemap.c:982
 page_cache_ra_unbounded+0x412/0x9b0 mm/readahead.c:282
 do_page_cache_ra mm/readahead.c:334 [inline]
 force_page_cache_ra+0x271/0x2e0 mm/readahead.c:364
 filemap_get_pages+0x47c/0x1ea0 mm/filemap.c:2690
 filemap_read+0x44a/0x1240 mm/filemap.c:2800
 blkdev_read_iter+0x311/0x440 block/fops.c:855
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x58b/0xa80 fs/read_write.c:574
 ksys_read+0x156/0x270 fs/read_write.c:717
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888057abd380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888057abd400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888057abd480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                 ^
 ffff888057abd500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888057abd580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================