fs/ecryptfs: Return -ENOMEM on memory allocation failure

In this code, 0 is returned on memory allocation failure, even though other
failures return -ENOMEM or other similar values.

A simplified version of the semantic match that finds this problem is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
expression ret;
expression x,e1,e2,e3;
@@

ret = 0
... when != ret = e1
*x = \(kmalloc\|kcalloc\|kzalloc\)(...)
... when != ret = e2
if (x == NULL) { ... when != ret = e3
  return ret;
}
// </smpl>
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Tyler Hicks <tyhicks@linux.vnet.ibm.com>

fs/ecryptfs/keystore.c

@@ -515,6 +515,7 @@ ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
 	if (!s) {
 		printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
 		       "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
+		rc = -ENOMEM;
 		goto out;
 	}
 	s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
@@ -806,6 +807,7 @@ ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
 	if (!s) {
 		printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
 		       "[%zd] bytes of kernel memory\n", __func__, sizeof(*s));
+		rc = -ENOMEM;
 		goto out;
 	}
 	s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;