sysctl binary: Reorder the tests to process wild card entries first.

A malicious user could have passed in a ctl_name of 0 and triggered
the well know ctl_name to procname mapping code, instead of the wild
card matching code.  This is a slight problem as wild card entries don't
have procnames, and because in some alternate universe a network device
might have ifindex 0.  So test for and handle wild card entries first.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>

1 files changed, 7 insertions, 8 deletions

diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 0cf60400542d..b75dbf40f573 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -1269,17 +1269,12 @@ repeat:
         for ( ; table->convert; table++) {
                 int len = 0;
 
-                /* Use the well known sysctl number to proc name mapping */
-                if (ctl_name == table->ctl_name) {
-                        len = strlen(table->procname);
-                        memcpy(path, table->procname, len);
-                }
-#ifdef CONFIG_NET
                 /*
                  * For a wild card entry map from ifindex to network
                  * device name.
                  */
-                else if (!table->ctl_name) {
+                if (!table->ctl_name) {
+#ifdef CONFIG_NET
                         struct net *net = current->nsproxy->net_ns;
                         struct net_device *dev;
                         dev = dev_get_by_index(net, ctl_name);
@@ -1288,8 +1283,12 @@ repeat:
                                 memcpy(path, dev->name, len);
                                 dev_put(dev);
                         }
-                }
 #endif
+                /* Use the well known sysctl number to proc name mapping */
+                } else if (ctl_name == table->ctl_name) {
+                        len = strlen(table->procname);
+                        memcpy(path, table->procname, len);
+                }
                 if (len) {
                         path += len;
                         if (table->child) {