Commit 86fc80f1 authored Dec 09, 2009 by Thomas Gleixner Committed by James Morris Dec 10, 2009

capabilities: Use RCU to protect task lookup in sys_capget



cap_get_target_pid() protects the task lookup with tasklist_lock.
security_capget() is called under tasklist_lock as well but
tasklist_lock does not protect anything there. The capabilities are
protected by RCU already.

So tasklist_lock only protects the lookup and prevents the task going
away, which can be done with rcu_read_lock() as well.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: James Morris <jmorris@namei.org>

parent 67fa4880

kernel/capability.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -135,7 +135,7 @@ static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
		if (pid && (pid != task_pid_vnr(current))) {
		struct task_struct *target;

		read_lock(&tasklist_lock);
		rcu_read_lock();

		target = find_task_by_vpid(pid);
		if (!target)
		@@ -143,7 +143,7 @@ static inline int cap_get_target_pid(pid_t pid, kernel_cap_t *pEp,
		else
		ret = security_capget(target, pEp, pIp, pPp);

		read_unlock(&tasklist_lock);
		rcu_read_unlock();
		} else
		ret = security_capget(current, pEp, pIp, pPp);