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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>
This commit is contained in:
Thomas Gleixner 2009-12-09 17:13:31 +01:00 committed by James Morris
parent 67fa4880c5
commit 86fc80f16e
1 changed files with 2 additions and 2 deletions
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4
kernel/capability.c
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@ -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);