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BUG: KASAN: use-after-free in copy_page_from_iter_atomic+0x8b4/0x1140 lib/iov_iter.c:820
Read of size 4096 at addr ffff88802248d000 by task kworker/u4:2/3712

CPU: 1 PID: 3712 Comm: kworker/u4:2 Not tainted 6.1.0-rc1-syzkaller-00427-gd47136c28015 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
Workqueue: loop5 loop_workfn
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1b1/0x28e lib/dump_stack.c:106
 print_address_description+0x74/0x340 mm/kasan/report.c:284
 print_report+0x107/0x1f0 mm/kasan/report.c:395
 kasan_report+0xcd/0x100 mm/kasan/report.c:495
 kasan_check_range+0x2a7/0x2e0 mm/kasan/generic.c:189
 memcpy+0x25/0x60 mm/kasan/shadow.c:65
 copy_page_from_iter_atomic+0x8b4/0x1140 lib/iov_iter.c:820
 generic_perform_write+0x35a/0x5e0 mm/filemap.c:3761
 __generic_file_write_iter+0x176/0x400 mm/filemap.c:3881
 generic_file_write_iter+0xab/0x310 mm/filemap.c:3913
 do_iter_write+0x6c2/0xc20 fs/read_write.c:861
 lo_write_bvec drivers/block/loop.c:249 [inline]
 lo_write_simple drivers/block/loop.c:271 [inline]
 do_req_filebacked drivers/block/loop.c:495 [inline]
 loop_handle_cmd drivers/block/loop.c:1864 [inline]
 loop_process_work+0x149f/0x2320 drivers/block/loop.c:1899
 process_one_work+0x877/0xdb0 kernel/workqueue.c:2289
 worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
 kthread+0x266/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:306
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0000892340 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2248d
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea0001b35488 ffffea0001b4cf48 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x100dc0(GFP_USER|__GFP_ZERO), pid 28761, tgid 28755 (syz-executor.5), ts 1578501707282, free_ts 1578525739951
 prep_new_page mm/page_alloc.c:2538 [inline]
 get_page_from_freelist+0x742/0x7c0 mm/page_alloc.c:4287
 __alloc_pages+0x259/0x560 mm/page_alloc.c:5554
 lbmLogInit fs/jfs/jfs_logmgr.c:1816 [inline]
 lmLogInit+0x30c/0x1c30 fs/jfs/jfs_logmgr.c:1270
 open_inline_log fs/jfs/jfs_logmgr.c:1175 [inline]
 lmLogOpen+0x4fd/0x1000 fs/jfs/jfs_logmgr.c:1069
 jfs_mount_rw+0xe7/0x710 fs/jfs/jfs_mount.c:253
 jfs_fill_super+0x675/0xc50 fs/jfs/super.c:565
 mount_bdev+0x26c/0x3a0 fs/super.c:1400
 legacy_get_tree+0xea/0x180 fs/fs_context.c:610
 vfs_get_tree+0x88/0x270 fs/super.c:1530
 do_new_mount+0x289/0xad0 fs/namespace.c:3040
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount+0x2d3/0x3c0 fs/namespace.c:3568
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0xb0 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:1458 [inline]
 free_pcp_prepare+0x80c/0x8f0 mm/page_alloc.c:1508
 free_unref_page_prepare mm/page_alloc.c:3386 [inline]
 free_unref_page+0x7d/0x5f0 mm/page_alloc.c:3482
 lbmLogShutdown fs/jfs/jfs_logmgr.c:1864 [inline]
 lmLogShutdown+0x4ad/0x920 fs/jfs/jfs_logmgr.c:1684
 lmLogClose+0x291/0x530 fs/jfs/jfs_logmgr.c:1460
 jfs_umount+0x297/0x370 fs/jfs/jfs_umount.c:116
 jfs_put_super+0x86/0x190 fs/jfs/super.c:194
 generic_shutdown_super+0x130/0x310 fs/super.c:491
 kill_block_super+0x79/0xd0 fs/super.c:1427
 deactivate_locked_super+0xa7/0xf0 fs/super.c:331
 cleanup_mnt+0x494/0x520 fs/namespace.c:1186
 task_work_run+0x243/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x124/0x150 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xb2/0x140 kernel/entry/common.c:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x26/0x60 kernel/entry/common.c:296
 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88802248cf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88802248cf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88802248d000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88802248d080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88802248d100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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