engine: bail out of voxcache_fetchvoxmodel() if the offsets found in...

engine: bail out of voxcache_fetchvoxmodel() if the offsets found in texturecache.index don't lead to the expected data

source/build/src/texcache.cpp

@@ -925,7 +925,13 @@ voxmodel_t* voxcache_fetchvoxmodel(const char* const cacheid)
     voxmodel_t* vm = (voxmodel_t*)Xcalloc(1, sizeof(voxmodel_t));
 
     texcache.dataFilePos = texcache.entries[i]->offset;
-    texcache_readdata(&voxd, sizeof(voxd));
+
+    if (texcache_readdata(&voxd, sizeof(voxd)) || voxd.compressed_size <= 0)
+    {
+        Xfree(vm);
+        return NULL;
+    }
+
     vm->mytexx = voxd.mytexx;
     vm->mytexy = voxd.mytexy;
     vm->qcnt = voxd.qcnt;
@@ -938,9 +944,15 @@ voxmodel_t* voxcache_fetchvoxmodel(const char* const cacheid)
     auto bytes = LZ4_decompress_safe(compressed_data, decompressed_data, voxd.compressed_size, totalsize);
     Xfree(compressed_data);
 
-    UNREFERENCED_PARAMETER(bytes);
     Bassert(bytes > 0);
 
+    if (bytes <= 0)
+    {
+        Xfree(decompressed_data);
+        Xfree(vm);
+        return NULL;
+    }
+
     vm->vertex = (GLfloat*)Xmalloc(vertexsize);
     Bmemcpy(vm->vertex, decompressed_data, vertexsize);