scm: Capture the full credentials of the scm sender

This patch corrects an erroneous update of credential's gid with uid
introduced in commit 257b5358b32f17 since 2.6.36.

Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: James Morris <jmorris@namei.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/scm.c

@@ -192,7 +192,7 @@ int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *p)
 					goto error;
 
 				cred->uid = cred->euid = p->creds.uid;
-				cred->gid = cred->egid = p->creds.uid;
+				cred->gid = cred->egid = p->creds.gid;
 				put_cred(p->cred);
 				p->cred = cred;
 			}