==================================================================
BUG: KASAN: use-after-free in ext4_ext_binsearch fs/ext4/extents.c:826 [inline]
BUG: KASAN: use-after-free in ext4_find_extent+0xba3/0xd80 fs/ext4/extents.c:945
Read of size 4 at addr ffff888168c1801c by task kworker/u4:6/31113

CPU: 0 PID: 31113 Comm: kworker/u4:6 Not tainted 5.10.161-syzkaller-00019-g416c4356f372 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023
Workqueue: writeback wb_workfn (flush-7:3)
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack_lvl+0x1e2/0x24b lib/dump_stack.c:118
 print_address_description+0x81/0x3c0 mm/kasan/report.c:233
 __kasan_report mm/kasan/report.c:419 [inline]
 kasan_report+0x1a4/0x1f0 mm/kasan/report.c:436
 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report_generic.c:308
 ext4_ext_binsearch fs/ext4/extents.c:826 [inline]
 ext4_find_extent+0xba3/0xd80 fs/ext4/extents.c:945
 ext4_ext_map_blocks+0x219/0x3a30 fs/ext4/extents.c:4097
 ext4_map_blocks+0xa93/0x1ee0 fs/ext4/inode.c:638
 mpage_map_one_extent+0x1bd/0x680 fs/ext4/inode.c:2441
 mpage_map_and_submit_extent fs/ext4/inode.c:2494 [inline]
 ext4_writepages+0x15e9/0x3710 fs/ext4/inode.c:2862
 do_writepages+0x13a/0x280 mm/page-writeback.c:2358
 __writeback_single_inode+0xb8/0x6e0 fs/fs-writeback.c:1467
 writeback_sb_inodes+0x999/0x1700 fs/fs-writeback.c:1730
 __writeback_inodes_wb fs/fs-writeback.c:1801 [inline]
 wb_writeback+0x4f4/0xc20 fs/fs-writeback.c:1907
 wb_check_old_data_flush fs/fs-writeback.c:2009 [inline]
 wb_do_writeback+0x995/0xbd0 fs/fs-writeback.c:2062
 wb_workfn+0xf8/0x3f0 fs/fs-writeback.c:2091
 process_one_work+0x726/0xc10 kernel/workqueue.c:2296
 worker_thread+0xb27/0x1550 kernel/workqueue.c:2442
 kthread+0x349/0x3d0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:299

The buggy address belongs to the page:
page:ffffea0005a30600 refcount:1 mapcount:0 mapping:ffff8881613541f0 index:0x1918 pfn:0x168c18
aops:shmem_aops ino:7dd5 dentry name:"memfd:syzkaller"
flags: 0x800000000008001e(referenced|uptodate|dirty|lru|swapbacked)
raw: 800000000008001e ffffea0005f296c8 ffffea0005e8fd48 ffff8881613541f0
raw: 0000000000001918 0000000000000000 00000001ffffffff ffff888111a04000
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff888111a04000
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Movable, gfp_mask 0x1100cca(GFP_HIGHUSER_MOVABLE), pid 6037, ts 2798516849645, free_ts 2798315036489
 set_page_owner include/linux/page_owner.h:35 [inline]
 post_alloc_hook mm/page_alloc.c:2386 [inline]
 prep_new_page mm/page_alloc.c:2392 [inline]
 get_page_from_freelist+0x755/0x810 mm/page_alloc.c:4073
 __alloc_pages_nodemask+0x3b6/0x890 mm/page_alloc.c:5160
 __alloc_pages include/linux/gfp.h:529 [inline]
 __alloc_pages_node include/linux/gfp.h:542 [inline]
 alloc_pages_node include/linux/gfp.h:556 [inline]
 alloc_pages include/linux/gfp.h:575 [inline]
 shmem_alloc_page mm/shmem.c:1582 [inline]
 shmem_alloc_and_acct_page+0x899/0xbf0 mm/shmem.c:1607
 shmem_getpage_gfp+0x8d4/0x25e0 mm/shmem.c:1920
 shmem_getpage mm/shmem.c:162 [inline]
 shmem_write_begin+0xc8/0x1b0 mm/shmem.c:2502
 generic_perform_write+0x309/0x5b0 mm/filemap.c:3468
 __generic_file_write_iter+0x23c/0x560 mm/filemap.c:3597
 generic_file_write_iter+0xaf/0x1c0 mm/filemap.c:3629
 call_write_iter include/linux/fs.h:1969 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0xc4a/0xf80 fs/read_write.c:605
 ksys_write+0x198/0x2c0 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:667
 do_syscall_64+0x34/0x70 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xc6
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:28 [inline]
 free_pages_prepare mm/page_alloc.c:1332 [inline]
 free_pcp_prepare+0x18c/0x1c0 mm/page_alloc.c:1406
 free_unref_page_prepare mm/page_alloc.c:3293 [inline]
 free_unref_page_list+0x11d/0x660 mm/page_alloc.c:3367
 release_pages+0xc24/0xc60 mm/swap.c:1082
 __pagevec_release+0x81/0xf0 mm/swap.c:1102
 pagevec_release include/linux/pagevec.h:88 [inline]
 shmem_undo_range+0x7ac/0x18d0 mm/shmem.c:966
 shmem_truncate_range mm/shmem.c:1070 [inline]
 shmem_evict_inode+0x228/0xa20 mm/shmem.c:1170
 evict+0x2a3/0x6c0 fs/inode.c:577
 iput_final fs/inode.c:1655 [inline]
 iput+0x61f/0x7d0 fs/inode.c:1681
 dentry_unlink_inode+0x2df/0x3d0 fs/dcache.c:374
 __dentry_kill+0x3e2/0x5d0 fs/dcache.c:579
 dentry_kill+0xc0/0x2a0 fs/dcache.c:692
 dput+0x175/0x320 fs/dcache.c:878
 __fput+0x540/0x7c0 fs/file_table.c:294
 ____fput+0x15/0x20 fs/file_table.c:314
 task_work_run+0x147/0x1b0 kernel/task_work.c:154
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop+0xc8/0xe0 kernel/entry/common.c:164

Memory state around the buggy address:
 ffff888168c17f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888168c17f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888168c18000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                            ^
 ffff888168c18080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888168c18100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================
EXT4-fs error (device loop3): ext4_ext_split:1071: inode #19: comm kworker/u4:6: p_ext > EXT_MAX_EXTENT!
EXT4-fs (loop3): Delayed block allocation failed for inode 19 at logical offset 0 with max blocks 16 with error 117
EXT4-fs (loop3): This should not happen!! Data will be lost