jffs2: NULL return of kmem_cache_zalloc should be handled

NULL return of kmem_cache_zalloc should be handled in jffs2_alloc_xattr_datum
and jff2_alloc_xattr_ref.
Signed-off-by: Zhouyi Zhou <yizhouzhou@ict.ac.cn>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

fs/jffs2/malloc.c

@@ -288,6 +288,8 @@ struct jffs2_xattr_datum *jffs2_alloc_xattr_datum(void)
 	struct jffs2_xattr_datum *xd;
 	xd = kmem_cache_zalloc(xattr_datum_cache, GFP_KERNEL);
 	dbg_memalloc("%p\n", xd);
+	if (!xd)
+		return NULL;
 
 	xd->class = RAWNODE_CLASS_XATTR_DATUM;
 	xd->node = (void *)xd;
@@ -306,6 +308,8 @@ struct jffs2_xattr_ref *jffs2_alloc_xattr_ref(void)
 	struct jffs2_xattr_ref *ref;
 	ref = kmem_cache_zalloc(xattr_ref_cache, GFP_KERNEL);
 	dbg_memalloc("%p\n", ref);
+	if (!ref)
+		return NULL;
 
 	ref->class = RAWNODE_CLASS_XATTR_REF;
 	ref->node = (void *)ref;