MdeModulePkg Variable: Update GetNextVariableName to follow UEFI 2.7

"The size must be large enough to fit input string supplied in
VariableName buffer" is added in the description for VariableNameSize.
And two cases of EFI_INVALID_PARAMETER are added.
1. The input values of VariableName and VendorGuid are not a name and
   GUID of an existing variable.
2. Null-terminator is not found in the first VariableNameSize bytes of
   the input VariableName buffer.

This patch is to update code to follow them.

Cc: Liming Gao <liming.gao@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Liming Gao <liming.gao@intel.com>

1 files changed, 44 insertions, 7 deletions

diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
index 0a325de165..71a6fd2093 100644
--- a/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
+++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/Variable.c
@@ -2905,8 +2905,11 @@ Done:
   @param[in]  VendorGuid    Variable Vendor Guid.

   @param[out] VariablePtr   Pointer to variable header address.

 

-  @return EFI_SUCCESS       Find the specified variable.

-  @return EFI_NOT_FOUND     Not found.

+  @retval EFI_SUCCESS           The function completed successfully.

+  @retval EFI_NOT_FOUND         The next variable was not found.

+  @retval EFI_INVALID_PARAMETER If VariableName is not an empty string, while VendorGuid is NULL.

+  @retval EFI_INVALID_PARAMETER The input values of VariableName and VendorGuid are not a name and

+                                GUID of an existing variable.

 

 **/

 EFI_STATUS

@@ -2926,6 +2929,19 @@ VariableServiceGetNextVariableInternal (
 

   Status = FindVariable (VariableName, VendorGuid, &Variable, &mVariableModuleGlobal->VariableGlobal, FALSE);

   if (Variable.CurrPtr == NULL || EFI_ERROR (Status)) {

+    //

+    // For VariableName is an empty string, FindVariable() will try to find and return

+    // the first qualified variable, and if FindVariable() returns error (EFI_NOT_FOUND)

+    // as no any variable is found, still go to return the error (EFI_NOT_FOUND).

+    //

+    if (VariableName[0] != 0) {

+      //

+      // For VariableName is not an empty string, and FindVariable() returns error as

+      // VariableName and VendorGuid are not a name and GUID of an existing variable,

+      // there is no way to get next variable, follow spec to return EFI_INVALID_PARAMETER.

+      //

+      Status = EFI_INVALID_PARAMETER;

+    }

     goto Done;

   }

 

@@ -3046,14 +3062,22 @@ Done:
   Caution: This function may receive untrusted input.

   This function may be invoked in SMM mode. This function will do basic validation, before parse the data.

 

-  @param VariableNameSize           Size of the variable name.

+  @param VariableNameSize           The size of the VariableName buffer. The size must be large

+                                    enough to fit input string supplied in VariableName buffer.

   @param VariableName               Pointer to variable name.

   @param VendorGuid                 Variable Vendor Guid.

 

-  @return EFI_INVALID_PARAMETER     Invalid parameter.

-  @return EFI_SUCCESS               Find the specified variable.

-  @return EFI_NOT_FOUND             Not found.

-  @return EFI_BUFFER_TO_SMALL       DataSize is too small for the result.

+  @retval EFI_SUCCESS               The function completed successfully.

+  @retval EFI_NOT_FOUND             The next variable was not found.

+  @retval EFI_BUFFER_TOO_SMALL      The VariableNameSize is too small for the result.

+                                    VariableNameSize has been updated with the size needed to complete the request.

+  @retval EFI_INVALID_PARAMETER     VariableNameSize is NULL.

+  @retval EFI_INVALID_PARAMETER     VariableName is NULL.

+  @retval EFI_INVALID_PARAMETER     VendorGuid is NULL.

+  @retval EFI_INVALID_PARAMETER     The input values of VariableName and VendorGuid are not a name and

+                                    GUID of an existing variable.

+  @retval EFI_INVALID_PARAMETER     Null-terminator is not found in the first VariableNameSize bytes of

+                                    the input VariableName buffer.

 

 **/

 EFI_STATUS

@@ -3065,6 +3089,7 @@ VariableServiceGetNextVariableName (
   )

 {

   EFI_STATUS              Status;

+  UINTN                   MaxLen;

   UINTN                   VarNameSize;

   VARIABLE_HEADER         *VariablePtr;

 

@@ -3072,6 +3097,18 @@ VariableServiceGetNextVariableName (
     return EFI_INVALID_PARAMETER;

   }

 

+  //

+  // Calculate the possible maximum length of name string, including the Null terminator.

+  //

+  MaxLen = *VariableNameSize / sizeof (CHAR16);

+  if ((MaxLen == 0) || (StrnLenS (VariableName, MaxLen) == MaxLen)) {

+    //

+    // Null-terminator is not found in the first VariableNameSize bytes of the input VariableName buffer,

+    // follow spec to return EFI_INVALID_PARAMETER.

+    //

+    return EFI_INVALID_PARAMETER;

+  }

+

   AcquireLockOnlyAtBootTime(&mVariableModuleGlobal->VariableGlobal.VariableServicesLock);

 

   Status = VariableServiceGetNextVariableInternal (VariableName, VendorGuid, &VariablePtr);