SELinux: Fix a potentially uninitialised variable in SELinux hooks

Fix a potentially uninitialised variable in SELinux hooks that's given a
pointer to the network address by selinux_parse_skb() passing a pointer back
through its argument list.  By restructuring selinux_parse_skb(), the compiler
can see that the error case need not set it as the caller will return
immediately.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0ffd8814af3ea81e0a90fb8f49667f4a7861f569..3eae30609702a098aa00e8c7b0dabfa1649432a2 100644 (file)
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3539,38 +3539,44 @@ out:
 #endif /* IPV6 */
 
 static int selinux_parse_skb(struct sk_buff *skb, struct avc_audit_data *ad,
-                            char **addrp, int src, u8 *proto)
+                            char **_addrp, int src, u8 *proto)
 {
-       int ret = 0;
+       char *addrp;
+       int ret;
 
        switch (ad->u.net.family) {
        case PF_INET:
                ret = selinux_parse_skb_ipv4(skb, ad, proto);
-               if (ret || !addrp)
-                       break;
-               *addrp = (char *)(src ? &ad->u.net.v4info.saddr :
-                                       &ad->u.net.v4info.daddr);
-               break;
+               if (ret)
+                       goto parse_error;
+               addrp = (char *)(src ? &ad->u.net.v4info.saddr :
+                                      &ad->u.net.v4info.daddr);
+               goto okay;
 
 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
        case PF_INET6:
                ret = selinux_parse_skb_ipv6(skb, ad, proto);
-               if (ret || !addrp)
-                       break;
-               *addrp = (char *)(src ? &ad->u.net.v6info.saddr :
-                                       &ad->u.net.v6info.daddr);
-               break;
+               if (ret)
+                       goto parse_error;
+               addrp = (char *)(src ? &ad->u.net.v6info.saddr :
+                                      &ad->u.net.v6info.daddr);
+               goto okay;
 #endif /* IPV6 */
        default:
-               break;
+               addrp = NULL;
+               goto okay;
        }
 
-       if (unlikely(ret))
-               printk(KERN_WARNING
-                      "SELinux: failure in selinux_parse_skb(),"
-                      " unable to parse packet\n");
-
+parse_error:
+       printk(KERN_WARNING
+              "SELinux: failure in selinux_parse_skb(),"
+              " unable to parse packet\n");
        return ret;
+
+okay:
+       if (_addrp)
+               *_addrp = addrp;
+       return 0;
 }
 
 /**