sched: Fix invalid free for tsk->se.dyn_affi_stats

hulk inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I5TIOZ


CVE: NA

--------------------------------

BUG: KASAN: double-free or invalid-free in sched_prefer_cpus_free[...]

Freed by task 0:
 save_stack mm/kasan/kasan.c:448 [inline]
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x120/0x228 mm/kasan/kasan.c:521
 kasan_slab_free+0x10/0x18 mm/kasan/kasan.c:528
 slab_free_hook mm/slub.c:1397 [inline]
 slab_free_freelist_hook mm/slub.c:1425 [inline]
 slab_free mm/slub.c:3004 [inline]
 kfree+0x84/0x250 mm/slub.c:3965
 sched_prefer_cpus_free+0x58/0x78 kernel/sched/core.c:7219
 free_task+0xb0/0xe8 kernel/fork.c:463
 __delayed_free_task+0x24/0x30 kernel/fork.c:1716
 __rcu_reclaim kernel/rcu/rcu.h:236 [inline]
 rcu_do_batch+0x200/0x5e0 kernel/rcu/tree.c:2584
 invoke_rcu_callbacks kernel/rcu/tree.c:2897 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2864 [inline]
 rcu_process_callbacks+0x470/0xb60 kernel/rcu/tree.c:2881
 __do_softirq+0x2d0/0xba0 kernel/softirq.c:292

Add init of 'tsk->se.dyn_affi_stats == NULL' in dup_task_struct().

Fixes: ebca52ab ("sched: Add statistics for scheduler dynamic affinity")
Signed-off-by: Hui Tang <tanghui20@huawei.com>
Reviewed-by: Zhang Qiao <zhangqiao22@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>

kernel/fork.c

@@ -893,6 +893,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
 
 #ifdef CONFIG_QOS_SCHED_DYNAMIC_AFFINITY
 	tsk->prefer_cpus = NULL;
+	tsk->se.dyn_affi_stats = NULL;
 #endif
 
 	setup_thread_stack(tsk, orig);