netprio_cgroup: fix wrong memory access when NETPRIO_CGROUP=m

When the netprio_cgroup module is not loaded, net_prio_subsys_id
is -1, and so sock_update_prioidx() accesses cgroup_subsys array
with negative index subsys[-1].

Make the code resembles cls_cgroup code, which is bug free.

Origionally-authored-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 5 deletions

diff --git a/net/core/sock.c b/net/core/sock.c
index 3e81fd2e3c75..02f8dfe320b7 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1171,13 +1171,10 @@ EXPORT_SYMBOL(sock_update_classid);
 
 void sock_update_netprioidx(struct sock *sk)
 {
-        struct cgroup_netprio_state *state;
         if (in_interrupt())
                 return;
-        rcu_read_lock();
-        state = task_netprio_state(current);
-        sk->sk_cgrp_prioidx = state ? state->prioidx : 0;
-        rcu_read_unlock();
+
+        sk->sk_cgrp_prioidx = task_netprioidx(current);
 }
 EXPORT_SYMBOL_GPL(sock_update_netprioidx);
 #endif