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BUG: KASAN: use-after-free in ext4_ext_rm_leaf fs/ext4/extents.c:2627 [inline]
BUG: KASAN: use-after-free in ext4_ext_remove_space+0x3211/0x42f0 fs/ext4/extents.c:2965
Read of size 4 at addr ffff88806689bc18 by task syz-executor/13919

CPU: 0 UID: 0 PID: 13919 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 ext4_ext_rm_leaf fs/ext4/extents.c:2627 [inline]
 ext4_ext_remove_space+0x3211/0x42f0 fs/ext4/extents.c:2965
 ext4_ext_truncate+0x17e/0x300 fs/ext4/extents.c:4484
 ext4_truncate+0xb50/0x1300 fs/ext4/inode.c:4614
 ext4_evict_inode+0x8cf/0xee0 fs/ext4/inode.c:261
 evict+0x504/0x9c0 fs/inode.c:810
 do_unlinkat+0x39f/0x570 fs/namei.c:4744
 __do_sys_unlink fs/namei.c:4783 [inline]
 __se_sys_unlink fs/namei.c:4781 [inline]
 __x64_sys_unlink+0x47/0x50 fs/namei.c:4781
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f894735e577
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 57 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd4fd92b18 EFLAGS: 00000206 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f894735e577
RDX: 00007ffd4fd92b40 RSI: 00007ffd4fd92bd0 RDI: 00007ffd4fd92bd0
RBP: 00007ffd4fd92bd0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000100 R11: 0000000000000206 R12: 00007ffd4fd93cc0
R13: 00007f89473e1d7d R14: 00000000001076c5 R15: 00007ffd4fd94d90
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x4b pfn:0x6689b
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 dead000000000100 dead000000000122 0000000000000000
raw: 000000000000004b 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 12527, tgid 12526 (syz.1.549), ts 843077107061, free_ts 843541390615
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x240/0x2a0 mm/page_alloc.c:1850
 prep_new_page mm/page_alloc.c:1858 [inline]
 get_page_from_freelist+0x28c0/0x2960 mm/page_alloc.c:3884
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5183
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2416
 folio_alloc_mpol_noprof+0x39/0xe0 mm/mempolicy.c:2435
 shmem_alloc_folio mm/shmem.c:1871 [inline]
 shmem_alloc_and_add_folio mm/shmem.c:1910 [inline]
 shmem_get_folio_gfp+0x633/0x1a70 mm/shmem.c:2533
 shmem_get_folio mm/shmem.c:2639 [inline]
 shmem_write_begin+0xef/0x2a0 mm/shmem.c:3289
 generic_perform_write+0x29d/0x8c0 mm/filemap.c:4242
 shmem_file_write_iter+0xfb/0x120 mm/shmem.c:3464
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5d5/0xb40 fs/read_write.c:686
 ksys_write+0x14b/0x260 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 12527 tgid 12526 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1394 [inline]
 free_unref_folios+0xc22/0x1860 mm/page_alloc.c:2963
 folios_put_refs+0x569/0x670 mm/swap.c:1002
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x49e/0x14b0 mm/shmem.c:1120
 shmem_truncate_range mm/shmem.c:1232 [inline]
 shmem_evict_inode+0x272/0xa70 mm/shmem.c:1360
 evict+0x504/0x9c0 fs/inode.c:810
 __dentry_kill+0x209/0x660 fs/dcache.c:669
 dput+0x19f/0x2b0 fs/dcache.c:911
 __fput+0x69d/0xa80 fs/file_table.c:476
 fput_close_sync+0x119/0x200 fs/file_table.c:573
 __do_sys_close fs/open.c:1589 [inline]
 __se_sys_close fs/open.c:1574 [inline]
 __x64_sys_close+0x7f/0x110 fs/open.c:1574
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff88806689bb00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806689bb80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88806689bc00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88806689bc80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806689bd00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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