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BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xbea/0xe30 fs/ext4/extents.c:946
Read of size 4 at addr ffff88811f37bd18 by task kworker/u4:51/12681

CPU: 1 PID: 12681 Comm: kworker/u4:51 Not tainted 5.15.178-syzkaller-00034-g5e1b899f19c3 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x151/0x1c0 lib/dump_stack.c:106
 print_address_description+0x87/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:427 [inline]
 kasan_report+0x179/0x1c0 mm/kasan/report.c:444
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_binsearch fs/ext4/extents.c:827 [inline]
 ext4_find_extent+0xbea/0xe30 fs/ext4/extents.c:946
 ext4_ext_map_blocks+0x269/0x7450 fs/ext4/extents.c:4165
 ext4_map_blocks+0xa60/0x1c70 fs/ext4/inode.c:673
 mpage_map_one_extent fs/ext4/inode.c:2420 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2473 [inline]
 ext4_writepages+0x1628/0x4000 fs/ext4/inode.c:2841
 do_writepages+0x40e/0x670 mm/page-writeback.c:2388
 __writeback_single_inode+0xdf/0xa70 fs/fs-writeback.c:1647
 writeback_sb_inodes+0xb2a/0x1920 fs/fs-writeback.c:1930
 wb_writeback+0x3c8/0x9f0 fs/fs-writeback.c:2106
 wb_do_writeback fs/fs-writeback.c:2253 [inline]
 wb_workfn+0x3d9/0x1110 fs/fs-writeback.c:2294
 process_one_work+0x6bb/0xc10 kernel/workqueue.c:2325
 worker_thread+0xad5/0x12a0 kernel/workqueue.c:2472
 kthread+0x421/0x510 kernel/kthread.c:337
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:287
 </TASK>

The buggy address belongs to the page:
page:ffffea00047cdec0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x100 pfn:0x11f37b
flags: 0x4000000000000000(zone=1)
raw: 4000000000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000000100 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 15590, ts 904262590589, free_ts 904495304027
 set_page_owner include/linux/page_owner.h:33 [inline]
 post_alloc_hook+0x1a3/0x1b0 mm/page_alloc.c:2605
 prep_new_page+0x1b/0x110 mm/page_alloc.c:2611
 get_page_from_freelist+0x3550/0x35d0 mm/page_alloc.c:4485
 __alloc_pages+0x27e/0x8f0 mm/page_alloc.c:5780
 __alloc_pages_node include/linux/gfp.h:591 [inline]
 alloc_pages_node include/linux/gfp.h:605 [inline]
 alloc_pages include/linux/gfp.h:618 [inline]
 shmem_alloc_page mm/shmem.c:1587 [inline]
 shmem_alloc_and_acct_page+0x4bd/0xa80 mm/shmem.c:1612
 shmem_getpage_gfp+0x1388/0x23c0 mm/shmem.c:1908
 shmem_getpage mm/shmem.c:152 [inline]
 shmem_write_begin+0xca/0x1b0 mm/shmem.c:2476
 generic_perform_write+0x2de/0x750 mm/filemap.c:3857
 __generic_file_write_iter+0x25b/0x4b0 mm/filemap.c:3985
 generic_file_write_iter+0xaf/0x1c0 mm/filemap.c:4017
 call_write_iter include/linux/fs.h:2204 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0xd5d/0x1110 fs/read_write.c:594
 ksys_write+0x199/0x2c0 fs/read_write.c:647
 __do_sys_write fs/read_write.c:659 [inline]
 __se_sys_write fs/read_write.c:656 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:656
 x64_sys_call+0x2f/0x9a0 arch/x86/include/generated/asm/syscalls_64.h:2
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:26 [inline]
 free_pages_prepare mm/page_alloc.c:1472 [inline]
 free_pcp_prepare mm/page_alloc.c:1544 [inline]
 free_unref_page_prepare+0x7c8/0x7d0 mm/page_alloc.c:3534
 free_unref_page_list+0x14b/0xa60 mm/page_alloc.c:3671
 release_pages+0x1310/0x1370 mm/swap.c:1009
 __pagevec_release+0x84/0x100 mm/swap.c:1029
 pagevec_release include/linux/pagevec.h:81 [inline]
 shmem_undo_range+0x604/0x1560 mm/shmem.c:965
 shmem_truncate_range mm/shmem.c:1064 [inline]
 shmem_evict_inode+0x215/0x9d0 mm/shmem.c:1146
 evict+0x529/0x930 fs/inode.c:647
 iput_final fs/inode.c:1769 [inline]
 iput+0x63b/0x7e0 fs/inode.c:1795
 dentry_unlink_inode+0x34e/0x430 fs/dcache.c:380
 __dentry_kill+0x447/0x660 fs/dcache.c:586
 dentry_kill+0xc0/0x2a0 fs/dcache.c:-1
 dput+0x45/0x80 fs/dcache.c:893
 __fput+0x59d/0x8c0 fs/file_table.c:319
 ____fput+0x15/0x20 fs/file_table.c:339
 task_work_run+0x129/0x190 kernel/task_work.c:188
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0xc4/0xe0 kernel/entry/common.c:181

Memory state around the buggy address:
 ffff88811f37bc00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811f37bc80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88811f37bd00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                            ^
 ffff88811f37bd80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88811f37be00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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