xfrm: Oops on error in pfkey_msg2xfrm_state()

BugLink: http://bugs.launchpad.net/bugs/1702863

commit 1e3d0c2c upstream.

There are some missing error codes here so we accidentally return NULL
instead of an error pointer.  It results in a NULL pointer dereference.

Fixes: df71837d ("[LSM-IPSec]: Security association restriction.")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

net/key/af_key.c

@@ -1147,8 +1147,10 @@ static struct xfrm_state * pfkey_msg2xfrm_state(struct net *net,
 		if (key)
 			keysize = (key->sadb_key_bits + 7) / 8;
 		x->aalg = kmalloc(sizeof(*x->aalg) + keysize, GFP_KERNEL);
-		if (!x->aalg)
+		if (!x->aalg) {
+			err = -ENOMEM;
 			goto out;
+		}
 		strcpy(x->aalg->alg_name, a->name);
 		x->aalg->alg_key_len = 0;
 		if (key) {
@@ -1167,8 +1169,10 @@ static struct xfrm_state * pfkey_msg2xfrm_state(struct net *net,
 				goto out;
 			}
 			x->calg = kmalloc(sizeof(*x->calg), GFP_KERNEL);
-			if (!x->calg)
+			if (!x->calg) {
+				err = -ENOMEM;
 				goto out;
+			}
 			strcpy(x->calg->alg_name, a->name);
 			x->props.calgo = sa->sadb_sa_encrypt;
 		} else {
@@ -1182,8 +1186,10 @@ static struct xfrm_state * pfkey_msg2xfrm_state(struct net *net,
 			if (key)
 				keysize = (key->sadb_key_bits + 7) / 8;
 			x->ealg = kmalloc(sizeof(*x->ealg) + keysize, GFP_KERNEL);
-			if (!x->ealg)
+			if (!x->ealg) {
+				err = -ENOMEM;
 				goto out;
+			}
 			strcpy(x->ealg->alg_name, a->name);
 			x->ealg->alg_key_len = 0;
 			if (key) {
@@ -1228,8 +1234,10 @@ static struct xfrm_state * pfkey_msg2xfrm_state(struct net *net,
 		struct xfrm_encap_tmpl *natt;
 
 		x->encap = kmalloc(sizeof(*x->encap), GFP_KERNEL);
-		if (!x->encap)
+		if (!x->encap) {
+			err = -ENOMEM;
 			goto out;
+		}
 
 		natt = x->encap;
 		n_type = ext_hdrs[SADB_X_EXT_NAT_T_TYPE-1];