netfilter: log: protect nf_log_register against double registering

[firefly-linux-kernel-4.4.55.git] / net / netfilter / nf_log.c

diff --git a/net/netfilter/nf_log.c b/net/netfilter/nf_log.c
index 5eaf047ed37facad0df59e70428c08ef8717a70d..9562e393fdf7e178b0c48bff25ace88495c2224f 100644 (file)
--- a/net/netfilter/nf_log.c
+++ b/net/netfilter/nf_log.c
@@ -75,6 +75,7 @@ EXPORT_SYMBOL(nf_log_unset);
 int nf_log_register(u_int8_t pf, struct nf_logger *logger)
 {
        int i;
+       int ret = 0;
 
        if (pf >= ARRAY_SIZE(init_net.nf.nf_loggers))
                return -EINVAL;
@@ -82,16 +83,25 @@ int nf_log_register(u_int8_t pf, struct nf_logger *logger)
        mutex_lock(&nf_log_mutex);
 
        if (pf == NFPROTO_UNSPEC) {
+               for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++) {
+                       if (rcu_access_pointer(loggers[i][logger->type])) {
+                               ret = -EEXIST;
+                               goto unlock;
+                       }
+               }
                for (i = NFPROTO_UNSPEC; i < NFPROTO_NUMPROTO; i++)
                        rcu_assign_pointer(loggers[i][logger->type], logger);
        } else {
-               /* register at end of list to honor first register win */
+               if (rcu_access_pointer(loggers[pf][logger->type])) {
+                       ret = -EEXIST;
+                       goto unlock;
+               }
                rcu_assign_pointer(loggers[pf][logger->type], logger);
        }
 
+unlock:
        mutex_unlock(&nf_log_mutex);
-
-       return 0;
+       return ret;
 }
 EXPORT_SYMBOL(nf_log_register);