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BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbc8/0xde0 fs/ext4/extents.c:953
Read of size 4 at addr ffff8880887ef9b4 by task kworker/u4:8/6071

CPU: 0 PID: 6071 Comm: kworker/u4:8 Not tainted 6.5.0-rc6-syzkaller-00253-g9e6c269de404 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Workqueue: writeback wb_workfn (flush-7:3)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0x163/0x540 mm/kasan/report.c:475
 kasan_report+0x175/0x1b0 mm/kasan/report.c:588
 ext4_ext_binsearch fs/ext4/extents.c:837 [inline]
 ext4_find_extent+0xbc8/0xde0 fs/ext4/extents.c:953
 ext4_ext_map_blocks+0x2d1/0x71d0 fs/ext4/extents.c:4101
 ext4_map_blocks+0xa2f/0x1cb0 fs/ext4/inode.c:621
 mpage_map_one_extent fs/ext4/inode.c:2159 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2212 [inline]
 ext4_do_writepages+0x1670/0x3da0 fs/ext4/inode.c:2677
 ext4_writepages+0x203/0x3e0 fs/ext4/inode.c:2766
 do_writepages+0x3a6/0x670 mm/page-writeback.c:2553
 __writeback_single_inode+0x155/0xfa0 fs/fs-writeback.c:1603
 writeback_sb_inodes+0x8e3/0x11d0 fs/fs-writeback.c:1894
 wb_writeback+0x44d/0xc60 fs/fs-writeback.c:2070
 wb_do_writeback fs/fs-writeback.c:2217 [inline]
 wb_workfn+0x400/0xff0 fs/fs-writeback.c:2257
 process_one_work+0x92c/0x12c0 kernel/workqueue.c:2600
 worker_thread+0xa63/0x1210 kernel/workqueue.c:2751
 kthread+0x2b8/0x350 kernel/kthread.c:389
 ret_from_fork+0x2e/0x60 arch/x86/kernel/process.c:145
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>

The buggy address belongs to the physical page:
page:ffffea000221fbc0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x887ef
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000001 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 13561, tgid 13560 (syz-executor.4), ts 594689761722, free_ts 595779827259
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1570
 prep_new_page mm/page_alloc.c:1577 [inline]
 get_page_from_freelist+0x31e8/0x3370 mm/page_alloc.c:3221
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4477
 __folio_alloc+0x13/0x30 mm/page_alloc.c:4509
 vma_alloc_folio+0x48a/0x9a0 mm/mempolicy.c:2253
 shmem_alloc_folio mm/shmem.c:1579 [inline]
 shmem_alloc_and_acct_folio+0x5e7/0xe10 mm/shmem.c:1603
 shmem_get_folio_gfp+0x120f/0x3470 mm/shmem.c:1948
 shmem_get_folio mm/shmem.c:2079 [inline]
 shmem_write_begin+0x172/0x4e0 mm/shmem.c:2573
 generic_perform_write+0x31b/0x630 mm/filemap.c:3923
 generic_file_write_iter+0xaf/0x310 mm/filemap.c:4044
 call_write_iter include/linux/fs.h:1877 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x782/0xaf0 fs/read_write.c:584
 ksys_write+0x1a0/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1161 [inline]
 free_unref_page_prepare+0x903/0xa30 mm/page_alloc.c:2348
 free_unref_page_list+0x596/0x830 mm/page_alloc.c:2489
 release_pages+0x2193/0x2470 mm/swap.c:1042
 __folio_batch_release+0x84/0x100 mm/swap.c:1062
 folio_batch_release include/linux/pagevec.h:83 [inline]
 shmem_undo_range+0x6af/0x1ba0 mm/shmem.c:954
 shmem_truncate_range mm/shmem.c:1049 [inline]
 shmem_evict_inode+0x258/0x9f0 mm/shmem.c:1164
 evict+0x2a4/0x620 fs/inode.c:664
 __dentry_kill+0x436/0x650 fs/dcache.c:607
 dentry_kill+0xbb/0x290
 dput+0x1f3/0x420 fs/dcache.c:913
 __fput+0x628/0x950 fs/file_table.c:392
 task_work_run+0x24a/0x300 kernel/task_work.c:179
 exit_task_work include/linux/task_work.h:38 [inline]
 do_exit+0x68f/0x2290 kernel/exit.c:874
 do_group_exit+0x206/0x2c0 kernel/exit.c:1024
 get_signal+0x1709/0x17e0 kernel/signal.c:2881
 arch_do_signal_or_restart+0x91/0x670 arch/x86/kernel/signal.c:308

Memory state around the buggy address:
 ffff8880887ef880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880887ef900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff8880887ef980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                     ^
 ffff8880887efa00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff8880887efa80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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