diff --git a/drivers/xen/privcmd.c b/drivers/xen/privcmd.c
index 15ba592..725a49a 100644
--- a/drivers/xen/privcmd.c
+++ b/drivers/xen/privcmd.c
@@ -1620,6 +1620,12 @@ static void privcmd_close(struct vm_area_struct *vma)
 	kvfree(pages);
 }
 
+static int privcmd_may_split(struct vm_area_struct *area, unsigned long addr)
+{
+	/* Forbid splitting, avoids double free via privcmd_close(). */
+	return -EINVAL;
+}
+
 static vm_fault_t privcmd_fault(struct vm_fault *vmf)
 {
 	printk(KERN_DEBUG "privcmd_fault: vma=%p %lx-%lx, pgoff=%lx, uv=%p\n",
@@ -1631,6 +1637,7 @@ static vm_fault_t privcmd_fault(struct vm_fault *vmf)
 
 static const struct vm_operations_struct privcmd_vm_ops = {
 	.close = privcmd_close,
+	.may_split = privcmd_may_split,
 	.fault = privcmd_fault
 };
 
diff --git a/drivers/xen/sys-hypervisor.c b/drivers/xen/sys-hypervisor.c
index b1bb01b..9192324 100644
--- a/drivers/xen/sys-hypervisor.c
+++ b/drivers/xen/sys-hypervisor.c
@@ -366,6 +366,8 @@ static ssize_t buildid_show(struct hyp_sysfs_attr *attr, char *buffer)
 			ret = sprintf(buffer, "<denied>");
 		return ret;
 	}
+	if (ret > PAGE_SIZE)
+		return -ENOSPC;
 
 	buildid = kmalloc(sizeof(*buildid) + ret, GFP_KERNEL);
 	if (!buildid)
@@ -373,8 +375,10 @@ static ssize_t buildid_show(struct hyp_sysfs_attr *attr, char *buffer)
 
 	buildid->len = ret;
 	ret = HYPERVISOR_xen_version(XENVER_build_id, buildid);
-	if (ret > 0)
-		ret = sprintf(buffer, "%s", buildid->buf);
+	if (ret > 0) {
+		/* Build id is binary, not a string. */
+		memcpy(buffer, buildid->buf, ret);
+	}
 	kfree(buildid);
 
 	return ret;