+/*
+ * The EFI_LOAD_OPTION descriptor has the following layout:
+ * u32 Attributes;
+ * u16 FilePathListLength;
+ * u16 Description[];
+ * efi_device_path_protocol_t FilePathList[];
+ * u8 OptionalData[];
+ *
+ * This function validates and unpacks the variable-size data fields.
+ */
+static
+bool efi_load_option_unpack(efi_load_option_unpacked_t *dest,
+ const efi_load_option_t *src, size_t size)
+{
+ const void *pos;
+ u16 c;
+ efi_device_path_protocol_t header;
+ const efi_char16_t *description;
+ const efi_device_path_protocol_t *file_path_list;
+
+ if (size < offsetof(efi_load_option_t, variable_data))
+ return false;
+ pos = src->variable_data;
+ size -= offsetof(efi_load_option_t, variable_data);
+
+ if ((src->attributes & ~EFI_LOAD_OPTION_MASK) != 0)
+ return false;
+
+ /* Scan description. */
+ description = pos;
+ do {
+ if (size < sizeof(c))
+ return false;
+ c = *(const u16 *)pos;
+ pos += sizeof(c);
+ size -= sizeof(c);
+ } while (c != L'\0');
+
+ /* Scan file_path_list. */
+ file_path_list = pos;
+ do {
+ if (size < sizeof(header))
+ return false;
+ header = *(const efi_device_path_protocol_t *)pos;
+ if (header.length < sizeof(header))
+ return false;
+ if (size < header.length)
+ return false;
+ pos += header.length;
+ size -= header.length;
+ } while ((header.type != EFI_DEV_END_PATH && header.type != EFI_DEV_END_PATH2) ||
+ (header.sub_type != EFI_DEV_END_ENTIRE));
+ if (pos != (const void *)file_path_list + src->file_path_list_length)
+ return false;
+
+ dest->attributes = src->attributes;
+ dest->file_path_list_length = src->file_path_list_length;
+ dest->description = description;
+ dest->file_path_list = file_path_list;
+ dest->optional_data_size = size;
+ dest->optional_data = size ? pos : NULL;
+
+ return true;
+}
+
+/*
+ * At least some versions of Dell firmware pass the entire contents of the
+ * Boot#### variable, i.e. the EFI_LOAD_OPTION descriptor, rather than just the
+ * OptionalData field.
+ *
+ * Detect this case and extract OptionalData.
+ */
+void efi_apply_loadoptions_quirk(const void **load_options, int *load_options_size)
+{
+ const efi_load_option_t *load_option = *load_options;
+ efi_load_option_unpacked_t load_option_unpacked;
+
+ if (!IS_ENABLED(CONFIG_X86))
+ return;
+ if (!load_option)
+ return;
+ if (*load_options_size < sizeof(*load_option))
+ return;
+ if ((load_option->attributes & ~EFI_LOAD_OPTION_BOOT_MASK) != 0)
+ return;
+
+ if (!efi_load_option_unpack(&load_option_unpacked, load_option, *load_options_size))
+ return;
+
+ efi_warn_once(FW_BUG "LoadOptions is an EFI_LOAD_OPTION descriptor\n");
+ efi_warn_once(FW_BUG "Using OptionalData as a workaround\n");
+
+ *load_options = load_option_unpacked.optional_data;
+ *load_options_size = load_option_unpacked.optional_data_size;
+}
+