[PATCH 1/2] efi_loader: fix efi_get_next_variable_name_mem()

[Heinrich Schuchardt]

The VariableNameSize parameter is in bytes but u16_strnlen() counts u16.

Fix the parameter check for null termination.

Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
---
 include/efi_variable.h       | 3 ++-
 lib/efi_loader/efi_var_mem.c | 6 +++---
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/efi_variable.h b/include/efi_variable.h
index 03a3ecb235..805e6c5f1e 100644
--- a/include/efi_variable.h
+++ b/include/efi_variable.h
@@ -268,7 +268,8 @@ const efi_guid_t *efi_auth_var_get_guid(const u16 *name);
  * efi_get_next_variable_name_mem() - Runtime common code across efi variable
  *                                    implementations for GetNextVariable()
  *                                    from the cached memory copy
- * @variable_name_size:	size of variable_name buffer in byte
+ *
+ * @variable_name_size:	size of variable_name buffer in bytes
  * @variable_name:	name of uefi variable's name in u16
  * @vendor:		vendor's guid
  *
diff --git a/lib/efi_loader/efi_var_mem.c b/lib/efi_loader/efi_var_mem.c
index 13909b1d26..0bac594e00 100644
--- a/lib/efi_loader/efi_var_mem.c
+++ b/lib/efi_loader/efi_var_mem.c
@@ -315,14 +315,14 @@ efi_get_next_variable_name_mem(efi_uintn_t *variable_name_size,
 			       u16 *variable_name, efi_guid_t *vendor)
 {
 	struct efi_var_entry *var;
-	efi_uintn_t old_size;
+	efi_uintn_t len, old_size;
 	u16 *pdata;
 
 	if (!variable_name_size || !variable_name || !vendor)
 		return EFI_INVALID_PARAMETER;
 
-	if (u16_strnlen(variable_name, *variable_name_size) ==
-	    *variable_name_size)
+	len = *variable_name_size >> 1;
+	if (u16_strnlen(variable_name, len) == len)
 		return EFI_INVALID_PARAMETER;
 
 	if (!efi_var_mem_find(vendor, variable_name, &var) && *variable_name)
-- 
2.37.2