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
Read of size 1 at addr ffff88819ea868a6 by task syz.4.452/7831

CPU: 0 UID: 0 PID: 7831 Comm: syz.4.452 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_report+0xba/0x230
 kasan_report+0x117/0x150
 strcmp+0x6b/0xc0
 hpfs_get_ea+0x134/0xee0
 hpfs_read_inode+0x1a6/0x1050
 hpfs_fill_super+0x123d/0x1fa0
 get_tree_bdev_flags+0x431/0x4f0
 vfs_get_tree+0x92/0x2a0
 do_new_mount+0x329/0xa50
 __se_sys_mount+0x31d/0x420
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fccc879bf4a
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:00007fccc967be58 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fccc967bee0 RCX: 00007fccc879bf4a
RDX: 000020000000a000 RSI: 0000200000009ec0 RDI: 00007fccc967bea0
RBP: 000020000000a000 R08: 00007fccc967bee0 R09: 0000000003200041
R10: 0000000003200041 R11: 0000000000000246 R12: 0000200000009ec0
R13: 00007fccc967bea0 R14: 0000000000009e15 R15: 0000200000000440
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xa5 pfn:0x19ea86
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000000 ffffea00067aa448 ffffea00067a8948 0000000000000000
raw: 00000000000000a5 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 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 7822, tgid 7821 (syz.4.448), ts 147494022467, free_ts 147502396523
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x24dc/0x2580
 __alloc_frozen_pages_noprof+0x18d/0x380
 alloc_pages_mpol+0x232/0x4a0
 folio_alloc_mpol_noprof+0x39/0x70
 shmem_alloc_and_add_folio+0x445/0xf80
 shmem_get_folio_gfp+0x5a9/0x1670
 shmem_fallocate+0x96f/0xec0
 vfs_fallocate+0x669/0x7e0
 __x64_sys_fallocate+0xc0/0x110
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 7822 tgid 7821 stack trace:
 __free_frozen_pages+0xbb9/0xd10
 __folio_put+0x227/0x2c0
 hpage_collapse_scan_file+0x4877/0x50a0
 madvise_collapse+0x42f/0xb30
 madvise_vma_behavior+0x10d5/0x4300
 madvise_walk_vmas+0x573/0xae0
 madvise_do_behavior+0x386/0x540
 do_madvise+0x1fa/0x2e0
 __x64_sys_madvise+0xa6/0xc0
 do_syscall_64+0xe2/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88819ea86780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88819ea86800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88819ea86880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                               ^
 ffff88819ea86900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88819ea86980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
