syzbot

WARNING: The mand mount option has been deprecated and
         and is ignored by this kernel. Remove the mand
         option from the mount to silence this warning.
=======================================================
hpfs: filesystem error: improperly stopped; already mounted read-only
hpfs: filesystem error: warning: spare dnodes used, try chkdsk
hpfs: You really don't want any checks? You are crazy...
hpfs: hpfs_map_sector(): read error
hpfs: code page support is disabled
==================================================================
BUG: KASAN: use-after-free in strcmp+0x6b/0xc0 lib/string.c:283
Read of size 1 at addr ffff88804aae88a6 by task syz.0.17/5979

CPU: 1 UID: 0 PID: 5979 Comm: syz.0.17 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
 strcmp+0x6b/0xc0 lib/string.c:283
 hpfs_get_ea+0x134/0xee0 fs/hpfs/ea.c:139
 hpfs_read_inode+0x1a6/0x1050 fs/hpfs/inode.c:63
 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:3763 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3839
 do_mount fs/namespace.c:4172 [inline]
 __do_sys_mount fs/namespace.c:4361 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4338
 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: 0033:0x7f13c020da8a
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:00007ffc15c2bd88 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007ffc15c2be10 RCX: 00007f13c020da8a
RDX: 0000200000000080 RSI: 0000200000009ec0 RDI: 00007ffc15c2bdd0
RBP: 0000200000000080 R08: 00007ffc15c2be10 R09: 0000000003a00041
R10: 0000000003a00041 R11: 0000000000000246 R12: 0000200000009ec0
R13: 00007ffc15c2bdd0 R14: 0000000000009e3e R15: 0000200000000040
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x55d9c6cde pfn:0x4aae8
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 ffffea000126aa88 ffffea00012aba88 0000000000000000
raw: 000000055d9c6cde 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 5942, tgid 5942 (dhcpcd-run-hook), ts 114195935390, free_ts 114670018901
 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:2490
 folio_alloc_mpol_noprof mm/mempolicy.c:2509 [inline]
 vma_alloc_folio_noprof+0xea/0x290 mm/mempolicy.c:2544
 folio_prealloc mm/memory.c:-1 [inline]
 alloc_anon_folio mm/memory.c:5209 [inline]
 do_anonymous_page mm/memory.c:5266 [inline]
 do_pte_missing+0x7f9/0x29e0 mm/memory.c:4475
 handle_pte_fault mm/memory.c:6317 [inline]
 __handle_mm_fault mm/memory.c:6455 [inline]
 handle_mm_fault+0xd0a/0x13c0 mm/memory.c:6624
 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 5942 tgid 5942 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
 free_pages_and_swap_cache+0x2e7/0x5b0 mm/swap_state.c:423
 __tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline]
 tlb_batch_pages_flush mm/mmu_gather.c:151 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:398 [inline]
 tlb_flush_mmu+0x6d3/0xa30 mm/mmu_gather.c:405
 tlb_finish_mmu+0xf9/0x230 mm/mmu_gather.c:530
 exit_mmap+0x498/0xa10 mm/mmap.c:1315
 __mmput+0xcb/0x3d0 kernel/fork.c:1175
 exit_mm+0x168/0x220 kernel/exit.c:581
 do_exit+0x6a2/0x23c0 kernel/exit.c:964
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1118
 __do_sys_exit_group kernel/exit.c:1129 [inline]
 __se_sys_exit_group kernel/exit.c:1127 [inline]
 __x64_sys_exit_group+0x3f/0x40 kernel/exit.c:1127
 x64_sys_call+0x221a/0x2240 arch/x86/include/generated/asm/syscalls_64.h:232
 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:
 ffff88804aae8780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804aae8800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88804aae8880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff88804aae8900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804aae8980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================