sys_getppid: add missing rcu_dereference
Mandeep Singh Baines [Thu, 8 Dec 2011 22:34:44 +0000 (14:34 -0800)]
In order to safely dereference current->real_parent inside an
rcu_read_lock, we need an rcu_dereference.

Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

kernel/timer.c

index dbaa624..9c3c62b 100644 (file)
@@ -1368,7 +1368,7 @@ SYSCALL_DEFINE0(getppid)
        int pid;
 
        rcu_read_lock();
-       pid = task_tgid_vnr(current->real_parent);
+       pid = task_tgid_vnr(rcu_dereference(current->real_parent));
        rcu_read_unlock();
 
        return pid;