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BUG: KASAN: use-after-free in copy_page_from_iter_atomic+0x872/0x1100 lib/iov_iter.c:820
Read of size 4096 at addr ffff88803eaac000 by task kworker/u4:8/4455

CPU: 1 PID: 4455 Comm: kworker/u4:8 Not tainted 6.1.46-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Workqueue: loop4 loop_workfn
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2cb lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:284 [inline]
 print_report+0x15f/0x4f0 mm/kasan/report.c:395
 kasan_report+0x136/0x160 mm/kasan/report.c:495
 kasan_check_range+0x27f/0x290 mm/kasan/generic.c:189
 memcpy+0x25/0x60 mm/kasan/shadow.c:65
 copy_page_from_iter_atomic+0x872/0x1100 lib/iov_iter.c:820
 generic_perform_write+0x36c/0x5e0 mm/filemap.c:3762
 __generic_file_write_iter+0x176/0x400 mm/filemap.c:3882
 generic_file_write_iter+0xab/0x310 mm/filemap.c:3914
 do_iter_write+0x6e6/0xc50 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:1882 [inline]
 loop_process_work+0x13ff/0x2200 drivers/block/loop.c:1917
 process_one_work+0x8aa/0x11f0 kernel/workqueue.c:2292
 worker_thread+0xa5f/0x1210 kernel/workqueue.c:2439
 kthread+0x26e/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:ffffea0000faab00 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x3eaac
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00007c4948 ffffea0001c33388 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 13148, tgid 13147 (syz-executor.4), ts 896293863160, free_ts 896915115926
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x18d/0x1b0 mm/page_alloc.c:2533
 prep_new_page mm/page_alloc.c:2540 [inline]
 get_page_from_freelist+0x32ed/0x3480 mm/page_alloc.c:4292
 __alloc_pages+0x28d/0x770 mm/page_alloc.c:5559
 lbmLogInit fs/jfs/jfs_logmgr.c:1816 [inline]
 lmLogInit+0x376/0x1c90 fs/jfs/jfs_logmgr.c:1270
 open_inline_log fs/jfs/jfs_logmgr.c:1175 [inline]
 lmLogOpen+0x552/0x1030 fs/jfs/jfs_logmgr.c:1069
 jfs_mount_rw+0xe3/0x640 fs/jfs/jfs_mount.c:253
 jfs_fill_super+0x67d/0xc40 fs/jfs/super.c:565
 mount_bdev+0x2c9/0x3f0 fs/super.c:1432
 legacy_get_tree+0xeb/0x180 fs/fs_context.c:611
 vfs_get_tree+0x88/0x270 fs/super.c:1562
 do_new_mount+0x28b/0xae0 fs/namespace.c:3040
 do_mount fs/namespace.c:3383 [inline]
 __do_sys_mount fs/namespace.c:3591 [inline]
 __se_sys_mount+0x2d5/0x3c0 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:1460 [inline]
 free_pcp_prepare mm/page_alloc.c:1510 [inline]
 free_unref_page_prepare+0xf63/0x1120 mm/page_alloc.c:3388
 free_unref_page+0x98/0x570 mm/page_alloc.c:3484
 lbmLogShutdown fs/jfs/jfs_logmgr.c:1864 [inline]
 lmLogShutdown+0x4f8/0x960 fs/jfs/jfs_logmgr.c:1684
 lmLogClose+0x293/0x530 fs/jfs/jfs_logmgr.c:1460
 jfs_umount+0x298/0x370 fs/jfs/jfs_umount.c:116
 jfs_put_super+0x86/0x180 fs/jfs/super.c:194
 generic_shutdown_super+0x130/0x340 fs/super.c:501
 kill_block_super+0x7a/0xe0 fs/super.c:1459
 deactivate_locked_super+0xa0/0x110 fs/super.c:332
 cleanup_mnt+0x490/0x520 fs/namespace.c:1186
 task_work_run+0x246/0x300 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:286 [inline]
 syscall_exit_to_user_mode+0x60/0x270 kernel/entry/common.c:297
 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
 ffff88803eaabf00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88803eaabf80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88803eaac000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88803eaac080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88803eaac100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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