Null-dereference in Tensorflow

Overview

Impact

The implementation of GetInitOp is vulnerable to a crash caused by dereferencing a null pointer:

const auto& init_op_sig_it =
    meta_graph_def.signature_def().find(kSavedModelInitOpSignatureKey);
if (init_op_sig_it != sig_def_map.end()) {
  *init_op_name = init_op_sig_it->second.outputs()
                      .find(kSavedModelInitOpSignatureKey)
                      ->second.name();
  return Status::OK();
}

Here, we have a nested map and we assume that if the first .find succeeds then so would be the search in the internal map. However, the maps are built based on the SavedModel protobuf format and a malicious user can alter that on disk before loading to cause the second .find to return nullptr.

Patches

We have patched the issue in GitHub commit 4f38b1ac8e42727e18a2f0bde06d3bee8e77b250.

The fix will be included in TensorFlow 2.8.0. We will also cherrypick this commit on TensorFlow 2.7.1, TensorFlow 2.6.3, and TensorFlow 2.5.3, as these are also affected and still in supported range.

For more information

Please consult our security guide for more information regarding the security model and how to contact us with issues and questions.

Affected packages

• tensorflow < 2.5.3
• tensorflow >= 2.6.0, < 2.6.3
• tensorflow >= 2.7.0, < 2.7.1
• tensorflow-cpu < 2.5.3
• tensorflow-cpu >= 2.6.0, < 2.6.3
• tensorflow-cpu >= 2.7.0, < 2.7.1
• tensorflow-gpu < 2.5.3
• tensorflow-gpu >= 2.6.0, < 2.6.3
• tensorflow-gpu >= 2.7.0, < 2.7.1

Remediation

Upgrade to a patched release:

• tensorflow 2.5.3
• tensorflow 2.6.3
• tensorflow 2.7.1
• tensorflow-cpu 2.5.3
• tensorflow-cpu 2.6.3
• tensorflow-cpu 2.7.1
• tensorflow-gpu 2.5.3
• tensorflow-gpu 2.6.3
• tensorflow-gpu 2.7.1