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BUG: KASAN: use-after-free in ext4_ext_remove_space+0x31a5/0x4260
Read of size 4 at addr ffff88819eb76c18 by task syz.3.129/6881

CPU: 1 UID: 0 PID: 6881 Comm: syz.3.129 Not tainted syzkaller #0 PREEMPT(full) 
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+0xca/0x240
 kasan_report+0x118/0x150
 ext4_ext_remove_space+0x31a5/0x4260
 ext4_ext_truncate+0x17e/0x300
 ext4_truncate+0xb3e/0x12e0
 ext4_evict_inode+0x85e/0xe60
 evict+0x5f4/0xae0
 __dentry_kill+0x209/0x660
 finish_dput+0xc9/0x480
 __fput+0x68e/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x694/0x22f0
 do_group_exit+0x21c/0x2d0
 get_signal+0x1285/0x1340
 arch_do_signal_or_restart+0x9a/0x7a0
 exit_to_user_mode_loop+0x87/0x4e0
 do_syscall_64+0x2b7/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fb44418f7c9
Code: Unable to access opcode bytes at 0x7fb44418f79f.
RSP: 002b:00007fb4450510e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: 0000000000000001 RBX: 00007fb4443e5fa8 RCX: 00007fb44418f7c9
RDX: 00000000000f4240 RSI: 0000000000000081 RDI: 00007fb4443e5fac
RBP: 00007fb4443e5fa0 R08: 3fffffffffffffff R09: 0000000000000000
R10: 0000000000000006 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fb4443e6038 R14: 00007ffd25518700 R15: 00007ffd255187e8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x57 pfn:0x19eb76
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000000 ffffea00067addc8 ffffea00067add48 0000000000000000
raw: 0000000000000057 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 0x152c4a(GFP_NOFS|__GFP_HIGHMEM|__GFP_MOVABLE|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_HARDWALL), pid 6881, tgid 6880 (syz.3.129), ts 101439152854, free_ts 102076380628
 post_alloc_hook+0x234/0x290
 get_page_from_freelist+0x24e0/0x2580
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 alloc_pages_noprof+0xa9/0x190
 folio_alloc_noprof+0x1e/0x30
 filemap_alloc_folio_noprof+0x107/0x470
 page_cache_ra_order+0x546/0xe50
 do_sync_mmap_readahead+0x66a/0x870
 filemap_fault+0x6ac/0x1290
 __do_fault+0x138/0x390
 do_pte_missing+0x2206/0x3330
 handle_mm_fault+0x1b26/0x32b0
 __get_user_pages+0x1650/0x29f0
 populate_vma_page_range+0x29f/0x3a0
 __mm_populate+0x24c/0x380
page last free pid 6881 tgid 6880 stack trace:
 free_unref_folios+0xdb3/0x14f0
 folios_put_refs+0x584/0x670
 truncate_inode_pages_range+0x346/0xd90
 ext4_evict_inode+0x1fc/0xe60
 evict+0x5f4/0xae0
 __dentry_kill+0x209/0x660
 finish_dput+0xc9/0x480
 __fput+0x68e/0xa70
 task_work_run+0x1d4/0x260
 do_exit+0x694/0x22f0
 do_group_exit+0x21c/0x2d0
 get_signal+0x1285/0x1340
 arch_do_signal_or_restart+0x9a/0x7a0
 exit_to_user_mode_loop+0x87/0x4e0
 do_syscall_64+0x2b7/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88819eb76b00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88819eb76b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88819eb76c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88819eb76c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88819eb76d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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