==================================================================
BUG: KASAN: use-after-free in ext4_ext_remove_space+0x31a5/0x4260
Read of size 4 at addr ffff8881bdbadc18 by task syz.0.4/5940

CPU: 1 UID: 0 PID: 5940 Comm: syz.0.4 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: 0033:0x7fa23dd8f7c9
Code: Unable to access opcode bytes at 0x7fa23dd8f79f.
RSP: 002b:00007fa23ec4b0e8 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
RAX: fffffffffffffe00 RBX: 00007fa23dfe6098 RCX: 00007fa23dd8f7c9
RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00007fa23dfe6098
RBP: 00007fa23dfe6090 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fa23dfe6128 R14: 00007ffc39305bb0 R15: 00007ffc39305c98
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x7fe3d924a pfn:0x1bdbad
flags: 0x57ff00000000000(node=1|zone=2|lastcpupid=0x7ff)
raw: 057ff00000000000 ffffea0006f6eb08 ffffea0006f6eb88 0000000000000000
raw: 00000007fe3d924a 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 0x140dca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO|__GFP_COMP), pid 5944, tgid 5943 (syz.1.12), ts 66002232638, free_ts 66269611237
 post_alloc_hook+0x234/0x290
 get_page_from_freelist+0x24e0/0x2580
 __alloc_frozen_pages_noprof+0x181/0x370
 alloc_pages_mpol+0x232/0x4a0
 vma_alloc_folio_noprof+0xe4/0x200
 folio_prealloc+0x30/0x180
 do_wp_page+0x1231/0x5810
 handle_mm_fault+0x14c5/0x32b0
 do_user_addr_fault+0xa7c/0x1380
 exc_page_fault+0x71/0xd0
 asm_exc_page_fault+0x26/0x30
page last free pid 5944 tgid 5943 stack trace:
 free_unref_folios+0xdb3/0x14f0
 folios_put_refs+0x584/0x670
 free_pages_and_swap_cache+0x277/0x520
 tlb_flush_mmu+0x3a0/0x680
 tlb_finish_mmu+0xc3/0x1d0
 vms_clear_ptes+0x42b/0x530
 vms_complete_munmap_vmas+0x206/0x8a0
 do_vmi_align_munmap+0x364/0x440
 do_vmi_munmap+0x253/0x2e0
 __vm_munmap+0x207/0x380
 __x64_sys_munmap+0x60/0x70
 do_syscall_64+0xec/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff8881bdbadb00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881bdbadb80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8881bdbadc00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff8881bdbadc80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8881bdbadd00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================
