syzbot

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BUG: KASAN: slab-use-after-free in __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
BUG: KASAN: slab-use-after-free in _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
Read of size 1 at addr ffff8880449d4cd8 by task syz-executor/5599

CPU: 0 UID: 0 PID: 5599 Comm: syz-executor Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120
 print_address_description+0x55/0x1e0 mm/kasan/report.c:378
 print_report+0x58/0x70 mm/kasan/report.c:482
 kasan_report+0x117/0x150 mm/kasan/report.c:595
 __kasan_check_byte+0x2a/0x40 mm/kasan/common.c:574
 kasan_check_byte include/linux/kasan.h:402 [inline]
 lock_acquire+0x84/0x350 kernel/locking/lockdep.c:5842
 __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:132 [inline]
 _raw_spin_lock_irqsave+0x40/0x60 kernel/locking/spinlock.c:166
 rt_mutex_slowunlock+0xbf/0x8b0 kernel/locking/rtmutex.c:1426
 shrink_dentry_list+0x2e3/0x5e0 fs/dcache.c:1222
 shrink_dcache_tree+0xe9/0x5d0 fs/dcache.c:-1
 shrink_dcache_parent fs/dcache.c:1693 [inline]
 d_invalidate+0xde/0x210 fs/dcache.c:1775
 proc_invalidate_siblings_dcache+0x3d3/0x6c0 fs/proc/inode.c:142
 release_task+0x1207/0x16f0 kernel/exit.c:291
 wait_task_zombie kernel/exit.c:1279 [inline]
 wait_consider_task+0x1966/0x2e30 kernel/exit.c:1506
 do_wait_thread kernel/exit.c:1569 [inline]
 __do_wait+0x155/0x740 kernel/exit.c:1687
 do_wait+0x1e7/0x510 kernel/exit.c:1721
 kernel_wait4+0x232/0x2b0 kernel/exit.c:1880
 __do_sys_wait4 kernel/exit.c:1908 [inline]
 __se_sys_wait4 kernel/exit.c:1904 [inline]
 __x64_sys_wait4+0x166/0x240 kernel/exit.c:1904
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f859124d60e
Code: 08 0f 85 a5 a8 ff ff 49 89 fb 48 89 f0 48 89 d7 48 89 ce 4c 89 c2 4d 89 ca 4c 8b 44 24 08 4c 8b 4c 24 10 4c 89 5c 24 08 0f 05 <c3> 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 80 00 00 00 00 48 83 ec 08
RSP: 002b:00007ffd018f5228 EFLAGS: 00000246 ORIG_RAX: 000000000000003d
RAX: ffffffffffffffda RBX: 00005555788c9500 RCX: 00007f859124d60e
RDX: 0000000040000001 RSI: 00007ffd018f52cc RDI: ffffffffffffffff
RBP: 00007ffd018f52cc R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000001388
R13: 00000000000927c0 R14: 000000000004f21b R15: 00007ffd018f5320
 </TASK>

Allocated by task 9021:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 unpoison_slab_object mm/kasan/common.c:340 [inline]
 __kasan_slab_alloc+0x6c/0x80 mm/kasan/common.c:366
 kasan_slab_alloc include/linux/kasan.h:253 [inline]
 slab_post_alloc_hook mm/slub.c:4569 [inline]
 slab_alloc_node mm/slub.c:4898 [inline]
 kmem_cache_alloc_lru_noprof+0x33c/0x680 mm/slub.c:4917
 __d_alloc+0x37/0x6f0 fs/dcache.c:1807
 d_alloc_parallel+0xe6/0x1610 fs/dcache.c:2671
 __lookup_slow+0x152/0x440 fs/namei.c:1900
 lookup_slow+0x53/0x70 fs/namei.c:1932
 walk_component fs/namei.c:2278 [inline]
 link_path_walk+0x1273/0x18d0 fs/namei.c:2649
 path_openat+0x2d5/0x38a0 fs/namei.c:4854
 do_file_open+0x23e/0x4a0 fs/namei.c:4887
 do_sys_openat2+0x113/0x200 fs/open.c:1364
 do_sys_open fs/open.c:1370 [inline]
 __do_sys_openat fs/open.c:1386 [inline]
 __se_sys_openat fs/open.c:1381 [inline]
 __x64_sys_openat+0x138/0x170 fs/open.c:1381
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 20:
 kasan_save_stack mm/kasan/common.c:57 [inline]
 kasan_save_track+0x3e/0x80 mm/kasan/common.c:78
 kasan_save_free_info+0x46/0x50 mm/kasan/generic.c:584
 poison_slab_object mm/kasan/common.c:253 [inline]
 __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285
 kasan_slab_free include/linux/kasan.h:235 [inline]
 slab_free_hook mm/slub.c:2689 [inline]
 slab_free mm/slub.c:6246 [inline]
 kmem_cache_free+0x187/0x6c0 mm/slub.c:6373
 rcu_do_batch kernel/rcu/tree.c:2617 [inline]
 rcu_core kernel/rcu/tree.c:2869 [inline]
 rcu_cpu_kthread+0x99e/0x1470 kernel/rcu/tree.c:2957
 smpboot_thread_fn+0x541/0xa50 kernel/smpboot.c:160
 kthread+0x388/0x470 kernel/kthread.c:436
 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

Last potentially related work creation:
 kasan_save_stack+0x3e/0x60 mm/kasan/common.c:57
 kasan_record_aux_stack+0xbd/0xd0 mm/kasan/generic.c:556
 __call_rcu_common kernel/rcu/tree.c:3131 [inline]
 call_rcu+0xee/0x890 kernel/rcu/tree.c:3251
 __dentry_kill+0x4a9/0x690 fs/dcache.c:737
 finish_dput+0xc9/0x480 fs/dcache.c:927
 proc_invalidate_siblings_dcache+0x3db/0x6c0 fs/proc/inode.c:143
 release_task+0x1207/0x16f0 kernel/exit.c:291
 exit_notify kernel/exit.c:776 [inline]
 do_exit+0x1674/0x22c0 kernel/exit.c:987
 do_group_exit+0x21b/0x2d0 kernel/exit.c:1117
 get_signal+0x125c/0x1310 kernel/signal.c:3037
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:238 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
 do_syscall_64+0x33e/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff8880449d4c08
 which belongs to the cache dentry of size 376
The buggy address is located 208 bytes inside of
 freed 376-byte region [ffff8880449d4c08, ffff8880449d4d80)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x449d4
head: order:1 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff8880368fff01
flags: 0x80000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0080000000000040 ffff88801b6e73c0 dead000000000100 dead000000000122
raw: 0000000000000000 0000000800120012 00000000f5000000 ffff8880368fff01
head: 0080000000000040 ffff88801b6e73c0 dead000000000100 dead000000000122
head: 0000000000000000 0000000800120012 00000000f5000000 ffff8880368fff01
head: 0080000000000001 ffffffffffffff81 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000002
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 1, migratetype Reclaimable, gfp_mask 0xd20d0(__GFP_RECLAIMABLE|__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 5601, tgid 5601 (syz-executor), ts 79951353404, free_ts 0
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x231/0x280 mm/page_alloc.c:1858
 prep_new_page mm/page_alloc.c:1866 [inline]
 get_page_from_freelist+0x27c8/0x2840 mm/page_alloc.c:3946
 __alloc_frozen_pages_noprof+0x18d/0x380 mm/page_alloc.c:5226
 alloc_slab_page mm/slub.c:3278 [inline]
 allocate_slab+0x77/0x660 mm/slub.c:3467
 new_slab mm/slub.c:3525 [inline]
 refill_objects+0x33c/0x3d0 mm/slub.c:7251
 refill_sheaf mm/slub.c:2816 [inline]
 __pcs_replace_empty_main+0x373/0x720 mm/slub.c:4651
 alloc_from_pcs mm/slub.c:4749 [inline]
 slab_alloc_node mm/slub.c:4883 [inline]
 kmem_cache_alloc_lru_noprof+0x433/0x680 mm/slub.c:4917
 __d_alloc+0x37/0x6f0 fs/dcache.c:1807
 d_alloc+0x4b/0x190 fs/dcache.c:1886
 lookup_one_qstr_excl+0xd8/0x360 fs/namei.c:1801
 __start_dirop fs/namei.c:2916 [inline]
 start_dirop+0x5c/0x90 fs/namei.c:2938
 simple_start_creating+0xcc/0x110 fs/libfs.c:2305
 debugfs_start_creating+0xdb/0x1a0 fs/debugfs/inode.c:394
 __debugfs_create_file+0x6f/0x400 fs/debugfs/inode.c:428
 debugfs_create_file_unsafe+0x3a/0x50 fs/debugfs/inode.c:509
 nsim_bpf_init+0x172/0x270 drivers/net/netdevsim/bpf.c:641
page_owner free stack trace missing

Memory state around the buggy address:
 ffff8880449d4b80: 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc
 ffff8880449d4c00: fc fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880449d4c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                    ^
 ffff8880449d4d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880449d4d80: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
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