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BUG: KASAN: use-after-free in memcpy_from_iter lib/iov_iter.c:73 [inline]
BUG: KASAN: use-after-free in iterate_bvec include/linux/iov_iter.h:122 [inline]
BUG: KASAN: use-after-free in iterate_and_advance2 include/linux/iov_iter.h:249 [inline]
BUG: KASAN: use-after-free in iterate_and_advance include/linux/iov_iter.h:271 [inline]
BUG: KASAN: use-after-free in __copy_from_iter lib/iov_iter.c:249 [inline]
BUG: KASAN: use-after-free in copy_page_from_iter_atomic+0x954/0x1db0 lib/iov_iter.c:481
Read of size 4096 at addr ffff88802a31b000 by task kworker/u8:5/950

CPU: 1 PID: 950 Comm: kworker/u8:5 Not tainted 6.8.0-syzkaller-08951-gfe46a7dd189e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Workqueue: loop3 loop_workfn
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
 print_address_description mm/kasan/report.c:377 [inline]
 print_report+0x169/0x550 mm/kasan/report.c:488
 kasan_report+0x143/0x180 mm/kasan/report.c:601
 kasan_check_range+0x282/0x290 mm/kasan/generic.c:189
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 memcpy_from_iter lib/iov_iter.c:73 [inline]
 iterate_bvec include/linux/iov_iter.h:122 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:249 [inline]
 iterate_and_advance include/linux/iov_iter.h:271 [inline]
 __copy_from_iter lib/iov_iter.c:249 [inline]
 copy_page_from_iter_atomic+0x954/0x1db0 lib/iov_iter.c:481
 generic_perform_write+0x39b/0x640 mm/filemap.c:3938
 shmem_file_write_iter+0xfc/0x120 mm/shmem.c:2926
 do_iter_readv_writev+0x5a6/0x800
 vfs_iter_write+0x244/0x5d0 fs/read_write.c:895
 lo_write_bvec drivers/block/loop.c:246 [inline]
 lo_write_simple drivers/block/loop.c:267 [inline]
 do_req_filebacked drivers/block/loop.c:491 [inline]
 loop_handle_cmd drivers/block/loop.c:1907 [inline]
 loop_process_work+0x13a3/0x1e60 drivers/block/loop.c:1942
 process_one_work kernel/workqueue.c:3254 [inline]
 process_scheduled_works+0xa02/0x1770 kernel/workqueue.c:3335
 worker_thread+0x86d/0xd70 kernel/workqueue.c:3416
 kthread+0x2f2/0x390 kernel/kthread.c:388
 ret_from_fork+0x4d/0x80 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:243
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0000a8c6c0 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2a31b
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000000 ffffea0001f18848 ffffea0001ec6888 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 5355, tgid 5352 (syz-executor.3), ts 89347769256, free_ts 89892800131
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1533
 prep_new_page mm/page_alloc.c:1540 [inline]
 get_page_from_freelist+0x33ea/0x3580 mm/page_alloc.c:3311
 __alloc_pages+0x256/0x680 mm/page_alloc.c:4569
 alloc_pages_mpol+0x3de/0x650 mm/mempolicy.c:2133
 lbmLogInit fs/jfs/jfs_logmgr.c:1816 [inline]
 lmLogInit+0x37a/0x1c90 fs/jfs/jfs_logmgr.c:1270
 open_inline_log fs/jfs/jfs_logmgr.c:1175 [inline]
 lmLogOpen+0x55e/0x1040 fs/jfs/jfs_logmgr.c:1069
 jfs_mount_rw+0xf1/0x6a0 fs/jfs/jfs_mount.c:257
 jfs_fill_super+0x681/0xc50 fs/jfs/super.c:565
 mount_bdev+0x20c/0x2d0 fs/super.c:1658
 legacy_get_tree+0xf0/0x190 fs/fs_context.c:662
 vfs_get_tree+0x92/0x2a0 fs/super.c:1779
 do_new_mount+0x2be/0xb40 fs/namespace.c:3352
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
 do_syscall_64+0xfd/0x240
 entry_SYSCALL_64_after_hwframe+0x6d/0x75
page last free pid 5104 tgid 5104 stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1140 [inline]
 free_unref_page_prepare+0x968/0xa90 mm/page_alloc.c:2346
 free_unref_page+0x37/0x3f0 mm/page_alloc.c:2486
 lbmLogShutdown fs/jfs/jfs_logmgr.c:1864 [inline]
 lmLogShutdown+0x4fc/0x970 fs/jfs/jfs_logmgr.c:1684
 lmLogClose+0x297/0x530 fs/jfs/jfs_logmgr.c:1460
 jfs_umount+0x2ce/0x3a0 fs/jfs/jfs_umount.c:114
 jfs_put_super+0x8a/0x190 fs/jfs/super.c:194
 generic_shutdown_super+0x138/0x2d0 fs/super.c:641
 kill_block_super+0x44/0x90 fs/super.c:1675
 deactivate_locked_super+0xc6/0x130 fs/super.c:472
 cleanup_mnt+0x426/0x4c0 fs/namespace.c:1267
 task_work_run+0x251/0x310 kernel/task_work.c:180
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:108 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:201 [inline]
 syscall_exit_to_user_mode+0x168/0x360 kernel/entry/common.c:212
 do_syscall_64+0x10a/0x240 arch/x86/entry/common.c:89
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Memory state around the buggy address:
 ffff88802a31af00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88802a31af80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88802a31b000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88802a31b080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88802a31b100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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