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>

1 files changed, 24 insertions, 18 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0ffd8814af3e..3eae30609702 100644
--- 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;
 }
 
 /**