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BUG: KASAN: use-after-free in copy_page_from_iter_atomic+0x8e3/0x1230 lib/iov_iter.c:978
Read of size 4096 at addr ffff88801fa90000 by task kworker/u4:2/3598

CPU: 1 PID: 3598 Comm: kworker/u4:2 Not tainted 5.15.115-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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+0x63/0x3b0 mm/kasan/report.c:248
 __kasan_report mm/kasan/report.c:434 [inline]
 kasan_report+0x16b/0x1c0 mm/kasan/report.c:451
 kasan_check_range+0x27e/0x290 mm/kasan/generic.c:189
 memcpy+0x25/0x60 mm/kasan/shadow.c:65
 copy_page_from_iter_atomic+0x8e3/0x1230 lib/iov_iter.c:978
 generic_perform_write+0x33a/0x5b0 mm/filemap.c:3784
 __generic_file_write_iter+0x243/0x4f0 mm/filemap.c:3903
 generic_file_write_iter+0xa7/0x1b0 mm/filemap.c:3935
 do_iter_readv_writev+0x594/0x7a0
 do_iter_write+0x1ea/0x760 fs/read_write.c:855
 lo_write_bvec+0x297/0x740 drivers/block/loop.c:316
 lo_write_simple drivers/block/loop.c:338 [inline]
 do_req_filebacked drivers/block/loop.c:656 [inline]
 loop_handle_cmd drivers/block/loop.c:2234 [inline]
 loop_process_work+0x2309/0x2af0 drivers/block/loop.c:2274
 process_one_work+0x8a1/0x10c0 kernel/workqueue.c:2307
 worker_thread+0xaca/0x1280 kernel/workqueue.c:2454
 kthread+0x3f6/0x4f0 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:298
 </TASK>

The buggy address belongs to the page:
page:ffffea00007ea400 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1fa90
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 ffffea00007ea448 ffffea0001b2b388 0000000000000000
raw: 0000000000000000 0000000000000000 00000000ffffffff 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 0x112c40(GFP_NOFS|__GFP_NOWARN|__GFP_NORETRY|__GFP_HARDWALL), pid 3687, ts 791921408714, free_ts 791543236257
 prep_new_page mm/page_alloc.c:2426 [inline]
 get_page_from_freelist+0x322a/0x33c0 mm/page_alloc.c:4159
 __alloc_pages+0x272/0x700 mm/page_alloc.c:5421
 __page_cache_alloc+0xd4/0x4a0 mm/filemap.c:1022
 page_cache_ra_unbounded+0x2b1/0x930 mm/readahead.c:216
 do_page_cache_ra mm/readahead.c:269 [inline]
 force_page_cache_ra+0x378/0x3e0 mm/readahead.c:301
 page_cache_sync_readahead include/linux/pagemap.h:833 [inline]
 filemap_get_pages mm/filemap.c:2551 [inline]
 filemap_read+0x71c/0x2980 mm/filemap.c:2634
 blkdev_read_iter+0x12a/0x180 block/fops.c:560
 call_read_iter include/linux/fs.h:2097 [inline]
 new_sync_read fs/read_write.c:404 [inline]
 vfs_read+0xa9f/0xe10 fs/read_write.c:485
 ksys_read+0x1a2/0x2c0 fs/read_write.c:623
 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+0x61/0xcb
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1340 [inline]
 free_pcp_prepare mm/page_alloc.c:1391 [inline]
 free_unref_page_prepare+0xc34/0xcf0 mm/page_alloc.c:3317
 free_unref_page+0x95/0x2d0 mm/page_alloc.c:3396
 lbmLogShutdown fs/jfs/jfs_logmgr.c:1872 [inline]
 lmLogShutdown+0x4f8/0x960 fs/jfs/jfs_logmgr.c:1692
 lmLogClose+0x293/0x530 fs/jfs/jfs_logmgr.c:1468
 jfs_umount+0x298/0x370 fs/jfs/jfs_umount.c:116
 jfs_put_super+0x86/0x180 fs/jfs/super.c:194
 generic_shutdown_super+0x136/0x2c0 fs/super.c:475
 kill_block_super+0x7a/0xe0 fs/super.c:1405
 deactivate_locked_super+0xa0/0x110 fs/super.c:335
 cleanup_mnt+0x44e/0x500 fs/namespace.c:1143
 task_work_run+0x129/0x1a0 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:175
 exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x5d/0x250 kernel/entry/common.c:301
 do_syscall_64+0x49/0xb0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x61/0xcb

Memory state around the buggy address:
 ffff88801fa8ff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88801fa8ff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88801fa90000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
                   ^
 ffff88801fa90080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88801fa90100: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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