kernel/sys.c: fix missing rcu protection for sys_getpriority()

find_task_by_vpid() is not safe without rcu_read_lock(). 2.6.33-rc7 got RCU protection for sys_setpriority() but missed it for sys_getpriority(). Signed-off-by: Tetsuo Handa <[email protected]> Cc: Oleg Nesterov <[email protected]> Cc: "Paul E. McKenney" <[email protected]> Acked-by: Serge Hallyn <[email protected]> Acked-by: Thomas Gleixner <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
cail · Feb 23, 2010 · 7011883 · 7011883
1 parent 5a2d419
commit 7011883
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/kernel/sys.c b/kernel/sys.c
@@ -222,6 +222,7 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
 	if (which > PRIO_USER || which < PRIO_PROCESS)
 		return -EINVAL;
 
+	rcu_read_lock();
 	read_lock(&tasklist_lock);
 	switch (which) {
 		case PRIO_PROCESS:
@@ -267,6 +268,7 @@ SYSCALL_DEFINE2(getpriority, int, which, int, who)
 	}
 out_unlock:
 	read_unlock(&tasklist_lock);
+	rcu_read_unlock();
 
 	return retval;
 }