efi_loader: efi_dp_part_node check dp_alloc return value

dp_alloc() may return NULL. This needs to be caught.

Fixes: 98d48bdf415e ("efi_loader: provide a function to create a partition node")
Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
index ebffb77..acae007 100644
--- a/lib/efi_loader/efi_device_path.c
+++ b/lib/efi_loader/efi_device_path.c
@@ -936,7 +936,8 @@
 		dpsize = sizeof(struct efi_device_path_hard_drive_path);
 	buf = dp_alloc(dpsize);
 
-	dp_part_node(buf, desc, part);
+	if (buf)
+		dp_part_node(buf, desc, part);
 
 	return buf;
 }
diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
index 39ea1a6..79b2809 100644
--- a/lib/efi_loader/efi_disk.c
+++ b/lib/efi_loader/efi_disk.c
@@ -415,6 +415,11 @@
 		struct efi_handler *handler;
 		void *protocol_interface;
 
+		if (!node) {
+			ret = EFI_OUT_OF_RESOURCES;
+			goto error;
+		}
+
 		/* Parent must expose EFI_BLOCK_IO_PROTOCOL */
 		ret = efi_search_protocol(parent, &efi_block_io_guid, &handler);
 		if (ret != EFI_SUCCESS)