Fix buffer overflow in MD3Loader (#5763)

Co-authored-by: Kim Kulling <[email protected]>

code/AssetLib/MD3/MD3Loader.cpp

@@ -724,6 +724,7 @@ void MD3Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
     std::vector<unsigned char> mBuffer2(fileSize);
     file->Read(&mBuffer2[0], 1, fileSize);
     mBuffer = &mBuffer2[0];
+    const unsigned char* bufferEnd = mBuffer + fileSize;
 
     pcHeader = (BE_NCONST MD3::Header *)mBuffer;
 
@@ -749,9 +750,15 @@ void MD3Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 
     // Navigate to the list of surfaces
     BE_NCONST MD3::Surface *pcSurfaces = (BE_NCONST MD3::Surface *)(mBuffer + pcHeader->OFS_SURFACES);
+    if ((const unsigned char*)pcSurfaces + sizeof(MD3::Surface) * pcHeader->NUM_SURFACES > bufferEnd) {
+        throw DeadlyImportError("MD3 surface headers are outside the file");
+    }
 
     // Navigate to the list of tags
     BE_NCONST MD3::Tag *pcTags = (BE_NCONST MD3::Tag *)(mBuffer + pcHeader->OFS_TAGS);
+    if ((const unsigned char*)pcTags + sizeof(MD3::Tag) * pcHeader->NUM_TAGS > bufferEnd) {
+        throw DeadlyImportError("MD3 tags are outside the file");
+    }
 
     // Allocate output storage
     pScene->mNumMeshes = pcHeader->NUM_SURFACES;
@@ -1026,6 +1033,10 @@ void MD3Importer::InternReadFile(const std::string &pFile, aiScene *pScene, IOSy
 
         for (unsigned int i = 0; i < pcHeader->NUM_TAGS; ++i, ++pcTags) {
             aiNode *nd = pScene->mRootNode->mChildren[i] = new aiNode();
+            if ((const unsigned char*)pcTags + sizeof(MD3::Tag) > bufferEnd) {
+                throw DeadlyImportError("MD3 tag is outside the file");
+            }
+
             nd->mName.Set((const char *)pcTags->NAME);
             nd->mParent = pScene->mRootNode;