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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 ffff88803d8e1898 by task kworker/u4:1/12

CPU: 1 PID: 12 Comm: kworker/u4:1 Not tainted 6.6.0-rc1-syzkaller-00014-ga747acc0b752 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
Workqueue: writeback wb_workfn (flush-7:0)
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+0x2cb/0x7150 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+0x15e7/0x3c90 fs/ext4/inode.c:2675
 ext4_writepages+0x203/0x3e0 fs/ext4/inode.c:2764
 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+0x781/0x1130 kernel/workqueue.c:2630
 process_scheduled_works kernel/workqueue.c:2703 [inline]
 worker_thread+0xabf/0x1060 kernel/workqueue.c:2784
 kthread+0x2b8/0x350 kernel/kthread.c:388
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0000f63840 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x3d8e1
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 16616, tgid 16614 (syz-executor.3), ts 454134127383, free_ts 454718297686
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1536
 prep_new_page mm/page_alloc.c:1543 [inline]
 get_page_from_freelist+0x31db/0x3360 mm/page_alloc.c:3170
 __alloc_pages+0x255/0x670 mm/page_alloc.c:4426
 __folio_alloc+0x13/0x30 mm/page_alloc.c:4458
 vma_alloc_folio+0x48a/0x9a0 mm/mempolicy.c:2259
 shmem_alloc_folio mm/shmem.c:1658 [inline]
 shmem_alloc_and_acct_folio+0x438/0x9b0 mm/shmem.c:1683
 shmem_get_folio_gfp+0xca4/0x2b60 mm/shmem.c:2020
 shmem_get_folio mm/shmem.c:2143 [inline]
 shmem_write_begin+0x170/0x300 mm/shmem.c:2688
 generic_perform_write+0x31b/0x630 mm/filemap.c:3942
 shmem_file_write_iter+0xfc/0x120 mm/shmem.c:2865
 call_write_iter include/linux/fs.h:1985 [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:1136 [inline]
 free_unref_page_prepare+0x8c3/0x9f0 mm/page_alloc.c:2312
 free_unref_page_list+0x596/0x830 mm/page_alloc.c:2451
 release_pages+0x2113/0x23f0 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+0x6ad/0x19c0 mm/shmem.c:1022
 shmem_truncate_range mm/shmem.c:1114 [inline]
 shmem_evict_inode+0x29e/0xa80 mm/shmem.c:1243
 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+0x60d/0x910 fs/file_table.c:392
 task_work_run+0x24a/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xd9/0x100 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x64/0x280 kernel/entry/common.c:296
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86

Memory state around the buggy address:
 ffff88803d8e1780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803d8e1800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88803d8e1880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88803d8e1900: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803d8e1980: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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