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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 ffff888020dc4000 by task kworker/u4:0/3658

CPU: 0 PID: 3658 Comm: kworker/u4:0 Not tainted 6.1.53-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/04/2023
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:ffffea0000837100 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x20dc4
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x100cc0(GFP_USER), pid 4967, tgid 4967 (syz-executor.3), ts 1183111175123, free_ts 1183060115080
 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
 __get_free_pages+0x8/0x30 mm/page_alloc.c:5609
 kasan_populate_vmalloc_pte+0x35/0xf0 mm/kasan/shadow.c:271
 apply_to_pte_range mm/memory.c:2635 [inline]
 apply_to_pmd_range mm/memory.c:2679 [inline]
 apply_to_pud_range mm/memory.c:2715 [inline]
 apply_to_p4d_range mm/memory.c:2751 [inline]
 __apply_to_page_range+0x9c5/0xcc0 mm/memory.c:2785
 alloc_vmap_area+0x1977/0x1ac0 mm/vmalloc.c:1646
 __get_vm_area_node+0x16c/0x360 mm/vmalloc.c:2505
 __vmalloc_node_range+0x394/0x1460 mm/vmalloc.c:3183
 alloc_thread_stack_node kernel/fork.c:311 [inline]
 dup_task_struct+0x3e5/0x6d0 kernel/fork.c:980
 copy_process+0x637/0x4020 kernel/fork.c:2090
 kernel_clone+0x222/0x920 kernel/fork.c:2674
 __do_sys_clone3 kernel/fork.c:2973 [inline]
 __se_sys_clone3+0x373/0x410 kernel/fork.c:2957
 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_remount+0x431/0x6a0 fs/jfs/super.c:466
 reconfigure_super+0x43a/0x870 fs/super.c:966
 vfs_fsconfig_locked fs/fsopen.c:254 [inline]
 __do_sys_fsconfig fs/fsopen.c:439 [inline]
 __se_sys_fsconfig+0x98b/0xec0 fs/fsopen.c:314
 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

Memory state around the buggy address:
 ffff888020dc3f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888020dc3f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888020dc4000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff888020dc4080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888020dc4100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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