================================================
WARNING: lock held when returning to user space!
6.18.0-rc7-next-20251128 #1 Not tainted
------------------------------------------------
syz-executor.6/74284 is leaving the kernel with locks still held!
1 lock held by syz-executor.6/74284:
 #0: ffff888015a10848 (&sb->s_type->i_mutex_key#30/1){+.+.}-{4:4}, at: start_creating_noperm+0x84/0xd0
Process accounting resumed
==================================================================
BUG: KASAN: slab-use-after-free in rwsem_down_write_slowpath+0x1522/0x1670
Read of size 4 at addr ffff88805adf0034 by task syz-executor.6/74836

CPU: 0 UID: 0 PID: 74836 Comm: syz-executor.6 Not tainted 6.18.0-rc7-next-20251128 #1 PREEMPT(voluntary) 
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xca/0x120
 print_report+0xcb/0x610
 kasan_report+0xca/0x100
 rwsem_down_write_slowpath+0x1522/0x1670
 down_write_nested+0x1c6/0x1f0
 start_creating_noperm+0x84/0xd0
 do_mq_open+0x25f/0x980
 __x64_sys_mq_open+0x14f/0x1e0
 do_syscall_64+0xbf/0x420
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa3e8521b19
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa3e5a97188 EFLAGS: 00000246 ORIG_RAX: 00000000000000f0
RAX: ffffffffffffffda RBX: 00007fa3e8634f60 RCX: 00007fa3e8521b19
RDX: 0000000000000033 RSI: 0000000000000040 RDI: 0000000020000040
RBP: 00007fa3e857bf6d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000020000080 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffea0b55b6f R14: 00007fa3e5a97300 R15: 0000000000022000
 </TASK>

Allocated by task 74262:
 kasan_save_stack+0x24/0x50
 kasan_save_track+0x14/0x30
 __kasan_slab_alloc+0x59/0x70
 kmem_cache_alloc_node_noprof+0x228/0x730
 copy_process+0x460/0x7230
 kernel_clone+0xea/0x7c0
 __do_sys_clone+0xce/0x120
 do_syscall_64+0xbf/0x420
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 73644:
 kasan_save_stack+0x24/0x50
 kasan_save_track+0x14/0x30
 kasan_save_free_info+0x3a/0x60
 __kasan_slab_free+0x43/0x70
 kmem_cache_free+0x2cd/0x660
 rcu_core+0x73c/0x1ed0
 handle_softirqs+0x1b1/0x740
 __irq_exit_rcu+0xc4/0x100
 irq_exit_rcu+0x9/0x20
 sysvec_apic_timer_interrupt+0x70/0x80
 asm_sysvec_apic_timer_interrupt+0x1a/0x20

Last potentially related work creation:
 kasan_save_stack+0x24/0x50
 kasan_record_aux_stack+0x89/0xa0
 __call_rcu_common.constprop.0+0x70/0xad0
 __free_event+0x411/0xc30
 perf_event_release_kernel+0x3ef/0x540
 perf_release+0x31/0x40
 __fput+0x401/0xb50
 task_work_run+0x172/0x280
 do_exit+0x856/0x2950
 do_group_exit+0xd3/0x2a0
 __x64_sys_exit_group+0x3e/0x50
 x64_sys_call+0x18d6/0x18e0
 do_syscall_64+0xbf/0x420
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Second to last potentially related work creation:
 kasan_save_stack+0x24/0x50
 kasan_record_aux_stack+0x89/0xa0
 __call_rcu_common.constprop.0+0x70/0xad0
 put_task_struct_rcu_user+0x75/0xc0
 __schedule+0x1003/0x46a0
 schedule+0xdb/0x390
 schedule_timeout+0x11a/0x280
 rcu_gp_fqs_loop+0x1c3/0x1030
 rcu_gp_kthread+0x4aa/0x680
 kthread+0x3c8/0x740
 ret_from_fork+0x67a/0x7a0
 ret_from_fork_asm+0x1a/0x30

The buggy address belongs to the object at ffff88805adf0000
 which belongs to the cache task_struct of size 6848
The buggy address is located 52 bytes inside of
 freed 6848-byte region [ffff88805adf0000, ffff88805adf1ac0)

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x5adf0
head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
memcg:ffff88800ced6c01
anon flags: 0x100000000000040(head|node=0|zone=1)
page_type: f5(slab)
raw: 0100000000000040 ffff88800944c640 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000040004 00000000f5000000 ffff88800ced6c01
head: 0100000000000040 ffff88800944c640 0000000000000000 dead000000000001
head: 0000000000000000 0000000000040004 00000000f5000000 ffff88800ced6c01
head: 0100000000000003 ffffea00016b7c01 00000000ffffffff 00000000ffffffff
head: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000008
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805adeff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88805adeff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88805adf0000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff88805adf0080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88805adf0100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================