net/netlabel: Add kmalloc NULL tests

The test on map4 should be a test on map6.

The semantic match that finds this problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

// <smpl>
@@
expression *x;
identifier f;
constant char *C;
@@

x = \(kmalloc\|kcalloc\|kzalloc\)(...);
... when != x == NULL
    when != x != NULL
    when != (x || ...)
(
kfree(x)
|
f(...,C,...,x,...)
|
*f(...,x,...)
|
*x->f
)
// </smpl>

Signed-off-by: Julia Lawall <julia@diku.dk>
Acked-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlabel/netlabel_kapi.c

@@ -151,7 +151,7 @@ int netlbl_cfg_unlbl_map_add(const char *domain,
 			addr6 = addr;
 			mask6 = mask;
 			map6 = kzalloc(sizeof(*map6), GFP_ATOMIC);
-			if (map4 == NULL)
+			if (map6 == NULL)
 				goto cfg_unlbl_map_add_failure;
 			map6->type = NETLBL_NLTYPE_UNLABELED;
 			ipv6_addr_copy(&map6->list.addr, addr6);