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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 ffff88803d1e6cf0 by task kworker/u4:4/72

CPU: 1 PID: 72 Comm: kworker/u4:4 Not tainted 6.7.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Workqueue: writeback wb_workfn (flush-7:1)
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+0x142/0x170 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/0x1cd0 fs/ext4/inode.c:621
 mpage_map_one_extent fs/ext4/inode.c:2169 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2222 [inline]
 ext4_do_writepages+0x15e7/0x3ca0 fs/ext4/inode.c:2685
 ext4_writepages+0x203/0x3e0 fs/ext4/inode.c:2774
 do_writepages+0x3a6/0x670 mm/page-writeback.c:2553
 __writeback_single_inode+0x155/0xfc0 fs/fs-writeback.c:1625
 writeback_sb_inodes+0x8e3/0x1220 fs/fs-writeback.c:1916
 wb_writeback+0x44d/0xc70 fs/fs-writeback.c:2092
 wb_do_writeback fs/fs-writeback.c:2239 [inline]
 wb_workfn+0x400/0xfb0 fs/fs-writeback.c:2279
 process_one_work kernel/workqueue.c:2627 [inline]
 process_scheduled_works+0x90f/0x1420 kernel/workqueue.c:2700
 worker_thread+0xa5f/0x1000 kernel/workqueue.c:2781
 kthread+0x2d3/0x370 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:242
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0000f47980 refcount:0 mapcount:0 mapping:0000000000000000 index:0x1 pfn:0x3d1e6
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 0x100cca(GFP_HIGHUSER_MOVABLE), pid 26693, tgid 26692 (syz-executor.4), ts 921312061153, free_ts 923221578260
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1537
 prep_new_page mm/page_alloc.c:1544 [inline]
 get_page_from_freelist+0x33ea/0x3570 mm/page_alloc.c:3312
 __alloc_pages+0x255/0x680 mm/page_alloc.c:4568
 alloc_pages_mpol+0x3de/0x640 mm/mempolicy.c:2133
 shmem_alloc_folio mm/shmem.c:1630 [inline]
 shmem_alloc_and_add_folio+0x24f/0xde0 mm/shmem.c:1670
 shmem_get_folio_gfp+0x7c3/0x1ee0 mm/shmem.c:2054
 shmem_get_folio mm/shmem.c:2136 [inline]
 shmem_write_begin+0x170/0x4c0 mm/shmem.c:2719
 generic_perform_write+0x31b/0x630 mm/filemap.c:3918
 shmem_file_write_iter+0xfc/0x120 mm/shmem.c:2895
 call_write_iter include/linux/fs.h:2020 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x792/0xb20 fs/read_write.c:584
 ksys_write+0x1a0/0x2c0 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0x45/0x110 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1137 [inline]
 free_unref_page_prepare+0x931/0xa60 mm/page_alloc.c:2347
 free_unref_page_list+0x5a0/0x840 mm/page_alloc.c:2533
 release_pages+0x2117/0x2400 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+0x6b5/0x1da0 mm/shmem.c:1004
 shmem_truncate_range mm/shmem.c:1113 [inline]
 shmem_evict_inode+0x29b/0xa60 mm/shmem.c:1241
 evict+0x2a4/0x630 fs/inode.c:666
 __dentry_kill+0x436/0x660 fs/dcache.c:607
 dentry_kill+0xbb/0x290
 dput+0x21e/0x470 fs/dcache.c:913
 __fput+0x60b/0x9e0 fs/file_table.c:402
 task_work_run+0x24a/0x300 kernel/task_work.c:180
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xde/0x100 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xb1/0x150 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x69/0x2a0 kernel/entry/common.c:296
 do_syscall_64+0x52/0x110 arch/x86/entry/common.c:89

Memory state around the buggy address:
 ffff88803d1e6b80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803d1e6c00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88803d1e6c80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                             ^
 ffff88803d1e6d00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803d1e6d80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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