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 ffff88803b700003 by task syz.8.921/9187

CPU: 1 UID: 0 PID: 9187 Comm: syz.8.921 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 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:3758 [inline]
 do_new_mount+0x341/0xd30 fs/namespace.c:3834
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4360
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0c8ed9e0ca
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:00007f0c8fc1be58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f0c8fc1bee0 RCX: 00007f0c8ed9e0ca
RDX: 0000200000002280 RSI: 0000200000000040 RDI: 00007f0c8fc1bea0
RBP: 0000200000002280 R08: 00007f0c8fc1bee0 R09: 0000000003200041
R10: 0000000003200041 R11: 0000000000000246 R12: 0000200000000040
R13: 00007f0c8fc1bea0 R14: 0000000000009e21 R15: 0000200000000000
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x13e7 pfn:0x3b700
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: f0(buddy)
raw: 00fff00000000000 ffffea0000fa0808 ffffea0000f0d008 0000000000000000
raw: 00000000000013e7 0000000000000005 00000000f0000000 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 8530, tgid 8530 (syz.4.756), ts 336864258122, free_ts 338538968185
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x24ba/0x2540 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_pages_mpol+0x235/0x490 mm/mempolicy.c:2490
 folio_alloc_mpol_noprof+0x39/0x160 mm/mempolicy.c:2509
 shmem_alloc_folio mm/shmem.c:1933 [inline]
 shmem_alloc_and_add_folio+0x442/0xf80 mm/shmem.c:1975
 shmem_get_folio_gfp+0x5a9/0x1670 mm/shmem.c:2564
 shmem_get_folio mm/shmem.c:2670 [inline]
 shmem_write_begin+0x16c/0x330 mm/shmem.c:3303
 generic_perform_write+0x2e2/0x8f0 mm/filemap.c:4325
 shmem_file_write_iter+0xf8/0x120 mm/shmem.c:3478
 __kernel_write_iter+0x41e/0x880 fs/read_write.c:621
 dump_emit_page fs/coredump.c:1304 [inline]
 dump_user_range+0xc19/0x12c0 fs/coredump.c:1378
 elf_core_dump+0x34c2/0x3ad0 fs/binfmt_elf.c:2109
 coredump_write+0x1216/0x1910 fs/coredump.c:1053
 do_coredump fs/coredump.c:1132 [inline]
 vfs_coredump+0x3807/0x4530 fs/coredump.c:1206
 get_signal+0x1107/0x1330 kernel/signal.c:3022
page last free pid 5634 tgid 5634 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 __free_pages_prepare mm/page_alloc.c:1402 [inline]
 free_unref_folios+0xcec/0x1480 mm/page_alloc.c:3004
 folios_put_refs+0x9ff/0xb40 mm/swap.c:1008
 folio_batch_release include/linux/folio_batch.h:101 [inline]
 shmem_undo_range+0x52c/0x1660 mm/shmem.c:1149
 shmem_truncate_range mm/shmem.c:1277 [inline]
 shmem_evict_inode+0x289/0xae0 mm/shmem.c:1407
 evict+0x61e/0xb10 fs/inode.c:841
 filename_unlinkat+0x43f/0x610 fs/namei.c:5572
 __do_sys_unlink fs/namei.c:5603 [inline]
 __se_sys_unlink+0x2e/0x140 fs/namei.c:5600
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88803b6fff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88803b6fff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88803b700000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88803b700080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803b700100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================