Add check when get boot option variable to avoid system hang.

Signed-off-by: ydong10
Reviewed-by: niruiyu

git-svn-id: https://edk2.svn.sourceforge.net/svnroot/edk2/trunk/edk2@12927 6f19259b-4bc3-4df7-8a09-765794883524

IntelFrameworkModulePkg/Library/GenericBdsLib/BdsMisc.c

@@ -390,6 +390,95 @@ BdsLibRegisterNewOption (
   return Status;
 }
 
+/**
+  Returns the size of a device path in bytes.
+
+  This function returns the size, in bytes, of the device path data structure 
+  specified by DevicePath including the end of device path node. If DevicePath 
+  is NULL, then 0 is returned. If the length of the device path is bigger than
+  MaxSize, also return 0 to indicate this is an invalidate device path.
+
+  @param  DevicePath         A pointer to a device path data structure.
+  @param  MaxSize            Max valid device path size. If big than this size, 
+                             return error.
+  
+  @retval 0                  An invalid device path.
+  @retval Others             The size of a device path in bytes.
+
+**/
+UINTN
+GetDevicePathSizeEx (
+  IN CONST EFI_DEVICE_PATH_PROTOCOL  *DevicePath,
+  IN UINTN                           MaxSize
+  )
+{
+  UINTN  Size;
+  UINTN  NodeSize;
+
+  if (DevicePath == NULL) {
+    return 0;
+  }
+
+  //
+  // Search for the end of the device path structure
+  //
+  Size = 0;
+  while (!IsDevicePathEnd (DevicePath)) {
+    NodeSize = DevicePathNodeLength (DevicePath);
+    if (NodeSize == 0) {
+      return 0;
+    }
+    Size += NodeSize;
+    if (Size > MaxSize) {
+      return 0;
+    }
+    DevicePath = NextDevicePathNode (DevicePath);
+  }
+  Size += DevicePathNodeLength (DevicePath);
+  if (Size > MaxSize) {
+    return 0;
+  }
+
+  return Size;
+}
+
+/**
+  Returns the length of a Null-terminated Unicode string. If the length is 
+  bigger than MaxStringLen, return length 0 to indicate that this is an 
+  invalidate string.
+
+  This function returns the number of Unicode characters in the Null-terminated
+  Unicode string specified by String. 
+
+  If String is NULL, then ASSERT().
+  If String is not aligned on a 16-bit boundary, then ASSERT().
+
+  @param  String           A pointer to a Null-terminated Unicode string.
+  @param  MaxStringLen     Max string len in this string.
+
+  @retval 0                An invalid string.
+  @retval Others           The length of String.
+
+**/
+UINTN
+StrSizeEx (
+  IN      CONST CHAR16              *String,
+  IN      UINTN                     MaxStringLen
+  )
+{
+  UINTN                             Length;
+
+  ASSERT (String != NULL && MaxStringLen != 0);
+  ASSERT (((UINTN) String & BIT0) == 0);
+
+  for (Length = 0; *String != L'\0' && MaxStringLen != Length; String++, Length++);
+
+  if (*String != L'\0' && MaxStringLen == Length) {
+    return 0;
+  }
+
+  return (Length + 1) * sizeof (*String);
+}
 
 /**
   Build the boot#### or driver#### option from the VariableName, the
@@ -417,11 +506,13 @@ BdsLibVariableToOption (
   UINT8                     *TempPtr;
   UINTN                     VariableSize;
   EFI_DEVICE_PATH_PROTOCOL  *DevicePath;
+  EFI_DEVICE_PATH_PROTOCOL  *TempPath;
   BDS_COMMON_OPTION         *Option;
   VOID                      *LoadOptions;
   UINT32                    LoadOptionsSize;
   CHAR16                    *Description;
   UINT8                     NumOff;
+  UINTN                     TempSize;
   //
   // Read the variable. We will never free this data.
   //
@@ -458,7 +549,11 @@ BdsLibVariableToOption (
   //
   // Get the option's description string size
   //
-  TempPtr     += StrSize ((CHAR16 *) TempPtr);
+  TempSize = StrSizeEx ((CHAR16 *) TempPtr, VariableSize);
+  if (TempSize == 0) {
+    return NULL;
+  }
+  TempPtr += TempSize;
 
   //
   // Get the option's device path
@@ -466,7 +561,26 @@ BdsLibVariableToOption (
   DevicePath =  (EFI_DEVICE_PATH_PROTOCOL *) TempPtr;
   TempPtr    += FilePathSize;
 
+  //
+  // Validation device path.
+  //
+  TempPath       = DevicePath;
+  while (FilePathSize > 0) {
+    TempSize = GetDevicePathSizeEx (TempPath, FilePathSize);
+    if (TempSize == 0) {
+      return NULL;
+    }
+    FilePathSize = (UINT16) (FilePathSize - TempSize);
+    TempPath    += TempSize;
+  }
+
+  //
+  // Get load opion data.
+  //
   LoadOptions     = TempPtr;
+  if (VariableSize < (UINTN)(TempPtr - Variable)) {
+    return NULL;
+  }
   LoadOptionsSize = (UINT32) (VariableSize - (UINTN) (TempPtr - Variable));
 
   //