EXT4-fs: Ignoring removed orlov option
EXT4-fs (loop8): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: none.
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BUG: KASAN: use-after-free in ext4_ext_remove_space+0x3170/0x4280
Read of size 4 at addr ffff8881a3527c18 by task syz.8.2449/16942

CPU: 1 UID: 0 PID: 16942 Comm: syz.8.2449 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_address_description+0x55/0x1e0
 print_report+0x58/0x70
 kasan_report+0x117/0x150
 ext4_ext_remove_space+0x3170/0x4280
 ext4_ext_truncate+0x17e/0x2f0
 ext4_truncate+0xb63/0x13b0
 ext4_setattr+0x106e/0x1c60
 notify_change+0xc1a/0xf40
 do_truncate+0x1c2/0x250
 path_openat+0x2f89/0x3860
 do_file_open+0x23e/0x4a0
 do_sys_openat2+0x113/0x200
 __x64_sys_open+0x11e/0x150
 do_syscall_64+0x14d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7855f9c799
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 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:00007f7856eb1028 EFLAGS: 00000246 ORIG_RAX: 0000000000000002
RAX: ffffffffffffffda RBX: 00007f7856215fa0 RCX: 00007f7855f9c799
RDX: 00000000000000dc RSI: 000000000004827e RDI: 0000200000000200
RBP: 00007f7856032c99 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f7856216038 R14: 00007f7856215fa0 R15: 00007ffeb6dbc9d8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x981 pfn:0x1a3527
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000000 ffffea00068d4a08 ffffea00068d4988 0000000000000000
raw: 0000000000000981 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 16899, tgid 16898 (syz.1.2433), ts 530600521929, free_ts 531445149718
 post_alloc_hook+0x231/0x280
 get_page_from_freelist+0x2418/0x24b0
 __alloc_frozen_pages_noprof+0x233/0x3d0
 alloc_pages_mpol+0x235/0x490
 folio_alloc_mpol_noprof+0x39/0x160
 shmem_alloc_and_add_folio+0x445/0xf80
 shmem_get_folio_gfp+0x4d4/0x1420
 shmem_fault+0x179/0x390
 __do_fault+0x3e7/0x590
 do_pte_missing+0x20e5/0x3530
 handle_mm_fault+0x1bd7/0x3170
 __get_user_pages+0x1683/0x2720
 populate_vma_page_range+0x29e/0x3c0
 __mm_populate+0x25f/0x390
 vm_mmap_pgoff+0x3aa/0x4f0
 do_syscall_64+0x14d/0xf80
page last free pid 16905 tgid 16898 stack trace:
 free_unref_folios+0xcec/0x1480
 folios_put_refs+0x9ff/0xb40
 shmem_undo_range+0x52c/0x1660
 shmem_evict_inode+0x240/0x9e0
 evict+0x61e/0xb10
 __dentry_kill+0x1a2/0x5e0
 finish_dput+0xc9/0x480
 __fput+0x691/0xa70
 task_work_run+0x1d9/0x270
 do_exit+0x926/0x2490
 do_group_exit+0x21b/0x2d0
 get_signal+0x1284/0x1330
 arch_do_signal_or_restart+0xbc/0x830
 exit_to_user_mode_loop+0x86/0x480
 do_syscall_64+0x32d/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8881a3527b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881a3527b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881a3527c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff8881a3527c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881a3527d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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