hpfs: You really don't want any checks? You are crazy...
hpfs: hpfs_map_sector(): read error
hpfs: code page support is disabled
hpfs: hpfs_map_sector(): read error
hpfs: hpfs_map_sector(): read error
==================================================================
BUG: KASAN: use-after-free in strcmp+0x67/0xb0 lib/string.c:400
Read of size 1 at addr ffff88807090a8a6 by task syz.1.279/5290

CPU: 1 PID: 5290 Comm: syz.1.279 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106
 print_address_description+0x60/0x2d0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0xdf/0x130 mm/kasan/report.c:451
 strcmp+0x67/0xb0 lib/string.c:400
 hpfs_get_ea+0x134/0xda0 fs/hpfs/ea.c:139
 hpfs_read_inode+0x679/0x1050 fs/hpfs/inode.c:77
 hpfs_fill_super+0x12ee/0x1f30 fs/hpfs/super.c:712
 mount_bdev+0x28a/0x3c0 fs/super.c:1400
 legacy_get_tree+0xe6/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x247/0xa40 fs/namespace.c:3034
 do_mount fs/namespace.c:3377 [inline]
 __do_sys_mount fs/namespace.c:3585 [inline]
 __se_sys_mount+0x2e3/0x3d0 fs/namespace.c:3562
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f08080370ca
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:00007f080628de58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f080628dee0 RCX: 00007f08080370ca
RDX: 000020000000a000 RSI: 0000200000009ec0 RDI: 00007f080628dea0
RBP: 000020000000a000 R08: 00007f080628dee0 R09: 0000000003a00041
R10: 0000000003a00041 R11: 0000000000000246 R12: 0000200000009ec0
R13: 00007f080628dea0 R14: 0000000000009e2f R15: 0000200000000000
 </TASK>

The buggy address belongs to the page:
page:ffffea0001c24280 refcount:1 mapcount:1 mapping:0000000000000000 index:0x7fe8004b7 pfn:0x7090a
memcg:ffff888076eb0000
anon flags: 0xfff00000080014(uptodate|lru|swapbacked|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000080014 ffffea0001c24248 ffffea0001c242c8 ffff8880793f1881
raw: 00000007fe8004b7 0000000000000000 0000000100000000 ffff888076eb0000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x1100dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), pid 5295, ts 166765468920, free_ts 166611678169
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x24f6/0x2670 mm/page_alloc.c:4192
 __alloc_pages+0x1ee/0x480 mm/page_alloc.c:5501
 alloc_pages_vma+0x2bc/0x790 mm/mempolicy.c:2146
 do_anonymous_page mm/memory.c:3838 [inline]
 handle_pte_fault mm/memory.c:4648 [inline]
 __handle_mm_fault mm/memory.c:4785 [inline]
 handle_mm_fault+0x23be/0x4440 mm/memory.c:4883
 do_user_addr_fault+0x494/0xc90 arch/x86/mm/fault.c:1355
 handle_page_fault arch/x86/mm/fault.c:1443 [inline]
 exc_page_fault+0x60/0x100 arch/x86/mm/fault.c:1496
 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0x637/0x6c0 mm/page_alloc.c:3317
 free_unref_page_list+0x119/0x830 mm/page_alloc.c:3433
 release_pages+0x185f/0x1bd0 mm/swap.c:963
 __pagevec_release+0x6d/0xe0 mm/swap.c:983
 pagevec_release include/linux/pagevec.h:81 [inline]
 shmem_undo_range+0x5cd/0x19a0 mm/shmem.c:964
 shmem_truncate_range mm/shmem.c:1063 [inline]
 shmem_evict_inode+0x1e2/0x9a0 mm/shmem.c:1145
 evict+0x4b6/0x8b0 fs/inode.c:647
 __dentry_kill+0x412/0x630 fs/dcache.c:586
 dentry_kill+0xb8/0x290 fs/dcache.c:-1
 dput+0xd8/0x1a0 fs/dcache.c:893
 __fput+0x5a5/0x8c0 fs/file_table.c:319
 task_work_run+0x125/0x1a0 kernel/task_work.c:188
 exit_task_work include/linux/task_work.h:33 [inline]
 do_exit+0x635/0x2110 kernel/exit.c:884
 do_group_exit+0x12c/0x2f0 kernel/exit.c:998
 get_signal+0x7eb/0x12e0 kernel/signal.c:2901
 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867

Memory state around the buggy address:
 ffff88807090a780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807090a800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88807090a880: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                               ^
 ffff88807090a900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88807090a980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================