Messages in this thread Patch in this message | | | Date | Wed, 9 Dec 2009 17:13:31 +0100 (CET) | From | Thomas Gleixner <> | Subject | [PATCH] capabilities: Use RCU to protect task lookup in sys_capget |
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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> --- kernel/capability.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6-tip/kernel/capability.c =================================================================== --- linux-2.6-tip.orig/kernel/capability.c +++ linux-2.6-tip/kernel/capability.c @@ -135,7 +135,7 @@ static inline int cap_get_target_pid(pid 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 else ret = security_capget(target, pEp, pIp, pPp); - read_unlock(&tasklist_lock); + rcu_read_unlock(); } else ret = security_capget(current, pEp, pIp, pPp);
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