mm/migrate: avoid possible unnecessary process right check in kernel_move_pages() (4dc200ce) · Commits · 戴 / test

mm/migrate.c

+43 −28

Original line number	Diff line number	Diff line
		@@ -1864,33 +1864,27 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
		return nr_pages ? -EFAULT : 0;
		}

		/*
		* Move a list of pages in the address space of the currently executing
		* process.
		*/
		static int kernel_move_pages(pid_t pid, unsigned long nr_pages,
		const void __user * __user *pages,
		const int __user *nodes,
		int __user *status, int flags)
		static struct mm_struct find_mm_struct(pid_t pid, nodemask_t mem_nodes)
		{
		struct task_struct *task;
		struct mm_struct *mm;
		int err;
		nodemask_t task_nodes;

		/* Check flags */
		if (flags & ~(MPOL_MF_MOVE\|MPOL_MF_MOVE_ALL))
		return -EINVAL;

		if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
		return -EPERM;
		/*
		* There is no need to check if current process has the right to modify
		* the specified process when they are same.
		*/
		if (!pid) {
		mmget(current->mm);
		*mem_nodes = cpuset_mems_allowed(current);
		return current->mm;
		}

		/* Find the mm_struct */
		rcu_read_lock();
		task = pid ? find_task_by_vpid(pid) : current;
		task = find_task_by_vpid(pid);
		if (!task) {
		rcu_read_unlock();
		return -ESRCH;
		return ERR_PTR(-ESRCH);
		}
		get_task_struct(task);

		@@ -1900,22 +1894,47 @@ static int kernel_move_pages(pid_t pid, unsigned long nr_pages,
		*/
		if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
		rcu_read_unlock();
		err = -EPERM;
		mm = ERR_PTR(-EPERM);
		goto out;
		}
		rcu_read_unlock();

		err = security_task_movememory(task);
		if (err)
		mm = ERR_PTR(security_task_movememory(task));
		if (IS_ERR(mm))
		goto out;

		task_nodes = cpuset_mems_allowed(task);
		*mem_nodes = cpuset_mems_allowed(task);
		mm = get_task_mm(task);
		out:
		put_task_struct(task);

		if (!mm)
		mm = ERR_PTR(-EINVAL);
		return mm;
		}

		/*
		* Move a list of pages in the address space of the currently executing
		* process.
		*/
		static int kernel_move_pages(pid_t pid, unsigned long nr_pages,
		const void __user * __user *pages,
		const int __user *nodes,
		int __user *status, int flags)
		{
		struct mm_struct *mm;
		int err;
		nodemask_t task_nodes;

		/* Check flags */
		if (flags & ~(MPOL_MF_MOVE\|MPOL_MF_MOVE_ALL))
		return -EINVAL;

		if ((flags & MPOL_MF_MOVE_ALL) && !capable(CAP_SYS_NICE))
		return -EPERM;

		mm = find_mm_struct(pid, &task_nodes);
		if (IS_ERR(mm))
		return PTR_ERR(mm);

		if (nodes)
		err = do_pages_move(mm, task_nodes, nr_pages, pages,
		nodes, status, flags);
		@@ -1924,10 +1943,6 @@ static int kernel_move_pages(pid_t pid, unsigned long nr_pages,

		mmput(mm);
		return err;

		out:
		put_task_struct(task);
		return err;
		}

		SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages,

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