efi_loader: correcty determine total device path length

Device paths may consist of multiple instances. Up to now we have only
considered the size of the first instance. For the services of the
EFI_DEVICE_PATH_UTILITIES_PROTOCOL in most cases the total length of the
device path is relevant.

So let's rename efi_dp_size() to efi_dp_instance_size() and create a new
function efi_dp_size() that calculates the total device path length.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Signed-off-by: Alexander Graf <agraf@suse.de>

2 files changed, 27 insertions, 11 deletions

diff --git a/lib/efi_loader/efi_boottime.c b/lib/efi_loader/efi_boottime.c
index 7a9449f59c..1cfdabf6eb 100644
--- a/lib/efi_loader/efi_boottime.c
+++ b/lib/efi_loader/efi_boottime.c
@@ -2219,7 +2219,7 @@ static efi_status_t EFIAPI efi_locate_device_path(
 	}
 
 	/* Find end of device path */
-	len = efi_dp_size(*device_path);
+	len = efi_dp_instance_size(*device_path);
 
 	/* Get all handles implementing the protocol */
 	ret = EFI_CALL(efi_locate_handle_buffer(BY_PROTOCOL, protocol, NULL,
@@ -2234,7 +2234,7 @@ static efi_status_t EFIAPI efi_locate_device_path(
 		if (ret != EFI_SUCCESS)
 			continue;
 		dp = (struct efi_device_path *)handler->protocol_interface;
-		len_dp = efi_dp_size(dp);
+		len_dp = efi_dp_instance_size(dp);
 		/*
 		 * This handle can only be a better fit
 		 * if its device path length is longer than the best fit and
diff --git a/lib/efi_loader/efi_device_path.c b/lib/efi_loader/efi_device_path.c
index a2e48851d7..ada0a9c268 100644
--- a/lib/efi_loader/efi_device_path.c
+++ b/lib/efi_loader/efi_device_path.c
@@ -149,7 +149,7 @@ static struct efi_object *find_obj(struct efi_device_path *dp, bool short_path,
 				   struct efi_device_path **rem)
 {
 	struct efi_object *efiobj;
-	unsigned int dp_size = efi_dp_size(dp);
+	efi_uintn_t dp_size = efi_dp_instance_size(dp);
 
 	list_for_each_entry(efiobj, &efi_obj_list, link) {
 		struct efi_handler *handler;
@@ -170,11 +170,12 @@ static struct efi_object *find_obj(struct efi_device_path *dp, bool short_path,
 					 * the caller.
 					 */
 					*rem = ((void *)dp) +
-						efi_dp_size(obj_dp);
+						efi_dp_instance_size(obj_dp);
 					return efiobj;
 				} else {
 					/* Only return on exact matches */
-					if (efi_dp_size(obj_dp) == dp_size)
+					if (efi_dp_instance_size(obj_dp) ==
+					    dp_size)
 						return efiobj;
 				}
 			}
@@ -229,10 +230,10 @@ const struct efi_device_path *efi_dp_last_node(const struct efi_device_path *dp)
 	return ret;
 }
 
-/* return size not including End node: */
-unsigned efi_dp_size(const struct efi_device_path *dp)
+/* get size of the first device path instance excluding end node */
+efi_uintn_t efi_dp_instance_size(const struct efi_device_path *dp)
 {
-	unsigned sz = 0;
+	efi_uintn_t sz = 0;
 
 	if (!dp || dp->type == DEVICE_PATH_TYPE_END)
 		return 0;
@@ -244,10 +245,25 @@ unsigned efi_dp_size(const struct efi_device_path *dp)
 	return sz;
 }
 
+/* get size of multi-instance device path excluding end node */
+efi_uintn_t efi_dp_size(const struct efi_device_path *dp)
+{
+	const struct efi_device_path *p = dp;
+
+	if (!p)
+		return 0;
+	while (p->type != DEVICE_PATH_TYPE_END ||
+	       p->sub_type != DEVICE_PATH_SUB_TYPE_END)
+		p = (void *)p + p->length;
+
+	return (void *)p - (void *)dp;
+}
+
+/* copy multi-instance device path */
 struct efi_device_path *efi_dp_dup(const struct efi_device_path *dp)
 {
 	struct efi_device_path *ndp;
-	unsigned sz = efi_dp_size(dp) + sizeof(END);
+	size_t sz = efi_dp_size(dp) + sizeof(END);
 
 	if (!dp)
 		return NULL;
@@ -298,7 +314,7 @@ struct efi_device_path *efi_dp_append_node(const struct efi_device_path *dp,
 	} else if (!node) {
 		ret = efi_dp_dup(dp);
 	} else if (!dp) {
-		unsigned sz = node->length;
+		size_t sz = node->length;
 		void *p = dp_alloc(sz + sizeof(END));
 		if (!p)
 			return NULL;
@@ -307,7 +323,7 @@ struct efi_device_path *efi_dp_append_node(const struct efi_device_path *dp,
 		ret = p;
 	} else {
 		/* both dp and node are non-null */
-		unsigned sz = efi_dp_size(dp);
+		size_t sz = efi_dp_size(dp);
 		void *p = dp_alloc(sz + node->length + sizeof(END));
 		if (!p)
 			return NULL;