kprobes: Free kretprobe_instance with RCU callback (b3388178) · Commits · 戴 / test

include/linux/kprobes.h

+4 −2

Original line number	Diff line number	Diff line
		@@ -156,7 +156,10 @@ struct kretprobe {
		};

		struct kretprobe_instance {
		union {
		struct hlist_node hlist;
		struct rcu_head rcu;
		};
		struct kretprobe *rp;
		kprobe_opcode_t *ret_addr;
		struct task_struct *task;
		@@ -395,7 +398,6 @@ int register_kretprobes(struct kretprobe **rps, int num);
		void unregister_kretprobes(struct kretprobe **rps, int num);

		void kprobe_flush_task(struct task_struct *tk);
		void recycle_rp_inst(struct kretprobe_instance ri, struct hlist_head head);

		int disable_kprobe(struct kprobe *kp);
		int enable_kprobe(struct kprobe *kp);

kernel/kprobes.c

+6 −19

Original line number	Diff line number	Diff line
		@@ -1223,8 +1223,7 @@ void kprobes_inc_nmissed_count(struct kprobe *p)
		}
		NOKPROBE_SYMBOL(kprobes_inc_nmissed_count);

		void recycle_rp_inst(struct kretprobe_instance *ri,
		struct hlist_head *head)
		static void recycle_rp_inst(struct kretprobe_instance *ri)
		{
		struct kretprobe *rp = ri->rp;

		@@ -1236,8 +1235,7 @@ void recycle_rp_inst(struct kretprobe_instance *ri,
		hlist_add_head(&ri->hlist, &rp->free_instances);
		raw_spin_unlock(&rp->lock);
		} else
		/* Unregistering */
		hlist_add_head(&ri->hlist, head);
		kfree_rcu(ri, rcu);
		}
		NOKPROBE_SYMBOL(recycle_rp_inst);

		@@ -1313,7 +1311,7 @@ void kprobe_busy_end(void)
		void kprobe_flush_task(struct task_struct *tk)
		{
		struct kretprobe_instance *ri;
		struct hlist_head *head, empty_rp;
		struct hlist_head *head;
		struct hlist_node *tmp;
		unsigned long hash, flags = 0;

		@@ -1323,19 +1321,14 @@ void kprobe_flush_task(struct task_struct *tk)

		kprobe_busy_begin();

		INIT_HLIST_HEAD(&empty_rp);
		hash = hash_ptr(tk, KPROBE_HASH_BITS);
		head = &kretprobe_inst_table[hash];
		kretprobe_table_lock(hash, &flags);
		hlist_for_each_entry_safe(ri, tmp, head, hlist) {
		if (ri->task == tk)
		recycle_rp_inst(ri, &empty_rp);
		recycle_rp_inst(ri);
		}
		kretprobe_table_unlock(hash, &flags);
		hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
		hlist_del(&ri->hlist);
		kfree(ri);
		}

		kprobe_busy_end();
		}
		@@ -1936,13 +1929,12 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
		void *frame_pointer)
		{
		struct kretprobe_instance ri = NULL, last = NULL;
		struct hlist_head *head, empty_rp;
		struct hlist_head *head;
		struct hlist_node *tmp;
		unsigned long flags;
		kprobe_opcode_t *correct_ret_addr = NULL;
		bool skipped = false;

		INIT_HLIST_HEAD(&empty_rp);
		kretprobe_hash_lock(current, &head, &flags);

		/*
		@@ -2011,7 +2003,7 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,
		__this_cpu_write(current_kprobe, prev);
		}

		recycle_rp_inst(ri, &empty_rp);
		recycle_rp_inst(ri);

		if (ri == last)
		break;
		@@ -2019,11 +2011,6 @@ unsigned long __kretprobe_trampoline_handler(struct pt_regs *regs,

		kretprobe_hash_unlock(current, &flags);

		hlist_for_each_entry_safe(ri, tmp, &empty_rp, hlist) {
		hlist_del(&ri->hlist);
		kfree(ri);
		}

		return (unsigned long)correct_ret_addr;
		}
		NOKPROBE_SYMBOL(__kretprobe_trampoline_handler)

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