Kernel bug: KASAN: use-after-free Read in ocfs2_check_dir_entry
Subsystem: ocfs2
Status: fixed

Crash report:
(kworker/u8:17,3565,1):ocfs2_read_blocks_sync:112 ERROR: status = -12
(kworker/u8:17,3565,1):ocfs2_read_locked_inode:599 ERROR: status = -12
==================================================================
BUG: KASAN: use-after-free in ocfs2_check_dir_entry+0x3a0/0x480 fs/ocfs2/dir.c:318
Read of size 2 at addr ffff888052e81780 by task kworker/u8:17/3565

CPU: 1 UID: 0 PID: 3565 Comm: kworker/u8:17 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: ocfs2_wq ocfs2_complete_recovery
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:378 [inline]
 print_report+0xca/0x240 mm/kasan/report.c:482
 kasan_report+0x118/0x150 mm/kasan/report.c:595
 ocfs2_check_dir_entry+0x3a0/0x480 fs/ocfs2/dir.c:318
 ocfs2_dir_foreach_blk_id fs/ocfs2/dir.c:1826 [inline]
 ocfs2_dir_foreach_blk+0xfff/0x1420 fs/ocfs2/dir.c:1954
 ocfs2_dir_foreach+0x42/0x70 fs/ocfs2/dir.c:1965
 ocfs2_queue_orphans fs/ocfs2/journal.c:2215 [inline]
 ocfs2_recover_orphans fs/ocfs2/journal.c:2299 [inline]
 ocfs2_complete_recovery+0xc37/0x20b0 fs/ocfs2/journal.c:1366
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0xad1/0x1770 kernel/workqueue.c:3340
 worker_thread+0x8a0/0xda0 kernel/workqueue.c:3421
 kthread+0x711/0x8a0 kernel/kthread.c:463
 ret_from_fork+0x599/0xb30 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x5c2 pfn:0x52e81
flags: 0x80000000000000(node=0|zone=1)
raw: 0080000000000000 ffffea00014ba088 ffffea00014ba008 0000000000000000
raw: 00000000000005c2 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 6060, tgid 6060 (syz.2.19), ts 112783813754, free_ts 113851953043
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x234/0x290 mm/page_alloc.c:1846
 prep_new_page mm/page_alloc.c:1854 [inline]
 get_page_from_freelist+0x28c0/0x2960 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x181/0x370 mm/page_alloc.c:5210
 alloc_pages_mpol+0xd1/0x380 mm/mempolicy.c:2486
 folio_alloc_mpol_noprof+0x39/0xe0 mm/mempolicy.c:2505
 shmem_alloc_folio mm/shmem.c:1890 [inline]
 shmem_alloc_and_add_folio mm/shmem.c:1932 [inline]
 shmem_get_folio_gfp+0x633/0x1a70 mm/shmem.c:2556
 shmem_get_folio mm/shmem.c:2662 [inline]
 shmem_write_begin+0x166/0x320 mm/shmem.c:3315
 generic_perform_write+0x29d/0x8c0 mm/filemap.c:4314
 shmem_file_write_iter+0xfb/0x120 mm/shmem.c:3490
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x5d5/0xb40 fs/read_write.c:686
 ksys_write+0x14b/0x260 fs/read_write.c:738
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
page last free pid 5931 tgid 5931 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1395 [inline]
 free_unref_folios+0xc28/0x1810 mm/page_alloc.c:3000
 folios_put_refs+0x569/0x670 mm/swap.c:1002
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x49e/0x1490 mm/shmem.c:1137
 shmem_truncate_range mm/shmem.c:1249 [inline]
 shmem_evict_inode+0x26e/0xa70 mm/shmem.c:1379
 evict+0x5f4/0xae0 fs/inode.c:837
 __dentry_kill+0x209/0x660 fs/dcache.c:670
 finish_dput+0xc9/0x480 fs/dcache.c:879
 __fput+0x69d/0xa80 fs/file_table.c:476
 task_work_run+0x1d4/0x260 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0xff/0x4f0 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x2e3/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888052e81680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888052e81700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888052e81780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff888052e81800: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888052e81880: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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