CVE-2021-37687 (published 2021-08-12T23:15Z)

TensorFlow is an end-to-end open source platform for machine learning. In affected versions TFLite's [`GatherNd` implementation](https://github.com/tensorflow/tensorflow/blob/149562d49faa709ea80df1d99fc41d005b81082a/tensorflow/lite/kernels/gather_nd.cc#L124) does not support negative indices but there are no checks for this situation. Hence, an attacker can read arbitrary data from the heap by carefully crafting a model with negative values in `indices`. Similar issue exists in [`Gather` implementation](https://github.com/tensorflow/tensorflow/blob/149562d49faa709ea80df1d99fc41d005b81082a/tensorflow/lite/kernels/gather.cc). We have patched the issue in GitHub commits bb6a0383ed553c286f87ca88c207f6774d5c4a8f and eb921122119a6b6e470ee98b89e65d721663179d. The fix will be included in TensorFlow 2.6.0. We will also cherrypick this commit on TensorFlow 2.5.1, TensorFlow 2.4.3, and TensorFlow 2.3.4, as these are also affected and still in supported range.

Severity: LOW
CVSS v2 base score: 2.1 (AV:L/AC:L/Au:N/C:P/I:N/A:N)
CVSS v3 base score: 5.5, MEDIUM (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N)

Weakness information:
cwe_id: CWE-125
cwe_name: Out-of-bounds Read
description: The product reads data past the end, or before the beginning, of the intended buffer.
extended_description: 
            
            
             
			 
         
         

Fix information:
repo_url: https://github.com/tensorflow/tensorflow
commit_details: repo_url: https://github.com/tensorflow/tensorflow
author: Mihai Maruseac
author_date: 2021-07-27 17:11:14-07:00
msg: Prevent heap OOB read in TFLite's `gather.cc`.

Passing negative indices is illegal but there was a missing check so that resulted in OOB accesses.

PiperOrigin-RevId: 387231300
Change-Id: I3111b54b2f232638d795be17efc46abe4ede6bf8
repository: repo_url: https://github.com/tensorflow/tensorflow
repo_name: tensorflow/tensorflow
description: An Open Source Machine Learning Framework for Everyone
repo_language: C++
owner: tensorflow
file_changes: filename: gather.cc
change_type: ModificationType.MODIFY
diff: @@ -117,8 +117,20 @@ TfLiteStatus Prepare(TfLiteContext* context, TfLiteNode* node) {
 }
 
 template <typename InputT, typename PositionsT>
-TfLiteStatus Gather(const TfLiteGatherParams& params, const TfLiteTensor* input,
-                    const TfLiteTensor* positions, TfLiteTensor* output) {
+TfLiteStatus Gather(TfLiteContext* context, const TfLiteGatherParams& params,
+                    const TfLiteTensor* input, const TfLiteTensor* positions,
+                    TfLiteTensor* output) {
+  const PositionsT* indexes = GetTensorData<PositionsT>(positions);
+  bool indices_has_only_positive_elements = true;
+  const size_t num_indices = positions->bytes / sizeof(PositionsT);
+  for (size_t i = 0; i < num_indices; i++) {
+    if (indexes[i] < 0) {
+      indices_has_only_positive_elements = false;
+      break;
+    }
+  }
+  TF_LITE_ENSURE(context, indices_has_only_positive_elements);
+
   tflite::GatherParams op_params;
   op_params.axis = params.axis;
   op_params.batch_dims = params.batch_dims;
@@ -134,7 +146,18 @@ TfLiteStatus GatherStrings(TfLiteContext* context, const TfLiteTensor* input,
                            const TfLiteTensor* positions,
                            TfLiteTensor* output) {
   DynamicBuffer buffer;
+
   const PositionT* indexes = GetTensorData<PositionT>(positions);
+  bool indices_has_only_positive_elements = true;
+  const size_t num_indices = positions->bytes / sizeof(PositionT);
+  for (size_t i = 0; i < num_indices; i++) {
+    if (indexes[i] < 0) {
+      indices_has_only_positive_elements = false;
+      break;
+    }
+  }
+  TF_LITE_ENSURE(context, indices_has_only_positive_elements);
+
   const PositionT num_strings = GetStringCount(input);
   const int num_indexes = NumElements(positions);
 
@@ -163,19 +186,26 @@ TfLiteStatus Eval(TfLiteContext* context, TfLiteNode* node) {
   if (positions->type == kTfLiteInt32) {
     switch (input->type) {
       case kTfLiteFloat32:
-        return Gather<float, int32_t>(*params, input, positions, output);
+        return Gather<float, int32_t>(context, *params, input, positions,
+                                      output);
       case kTfLiteUInt8:
-        return Gather<uint8_t, int32_t>(*params, input, positions, output);
+        return Gather<uint8_t, int32_t>(context, *params, input, positions,
+                                        output);
       case kTfLiteInt8:
-        return Gather<int8_t, int32_t>(*params, input, positions, output);
+        return Gather<int8_t, int32_t>(context, *params, input, positions,
+                                       output);
       case kTfLiteInt16:
-        return Gather<int16_t, int32_t>(*params, input, positions, output);
+        return Gather<int16_t, int32_t>(context, *params, input, positions,
+                                        output);
       case kTfLiteInt32:
-        return Gather<int32_t, int32_t>(*params, input, positions, output);
+        return Gather<int32_t, int32_t>(context, *params, input, positions,
+                                        output);
       case kTfLiteInt64:
-        return Gather<int64_t, int32_t>(*params, input, positions, output);
+        return Gather<int64_t, int32_t>(context, *params, input, positions,
+                                        output);
       case kTfLiteBool:
-        return Gather<bool, int32_t>(*params, input, positions, output);
+        return Gather<bool, int32_t>(context, *params, input, positions,
+                                     output);
       case kTfLiteString:
         return GatherStrings<int32_t>(context, input, positions, output);
       default:
@@ -187,19 +217,26 @@ TfLiteStatus Eval(TfLiteContext* context, TfLiteNode* node) {
   if (positions->type == kTfLiteInt64) {
     switch (input->type) {
       case kTfLiteFloat32:
-        return Gather<float, int64_t>(*params, input, positions, output);
+        return Gather<float, int64_t>(context, *params, input, positions,
+                                      output);
       case kTfLiteUInt8:
-        return Gather<uint8_t, int64_t>(*params, input, positions, output);
+        return Gather<uint8_t, int64_t>(context, *params, input, positions,
+                                        output);
       case kTfLiteInt8:
-        return Gather<int8_t, int64_t>(*params, input, positions, output);
+        return Gather<int8_t, int64_t>(context, *params, input, positions,
+                                       output);
       case kTfLiteInt16:
-        return Gather<int16_t, int64_t>(*params, input, positions, output);
+        return Gather<int16_t, int64_t>(context, *params, input, positions,
+                                        output);
       case kTfLiteInt32:
-        return Gather<int32_t, int64_t>(*params, input, positions, output);
+        return Gather<int32_t, int64_t>(context, *params, input, positions,
+                                        output);
       case kTfLiteInt64:
-        return Gather<int64_t, int64_t>(*params, input, positions, output);
+        return Gather<int64_t, int64_t>(context, *params, input, positions,
+                                        output);
       case kTfLiteBool:
-        return Gather<bool, int64_t>(*params, input, positions, output);
+        return Gather<bool, int64_t>(context, *params, input, positions,
+                                     output);
       case kTfLiteString:
         return GatherStrings<int64_t>(context, input, positions, output);
       default:

programming_language: C++
repo_url: https://github.com/tensorflow/tensorflow
commit_details: repo_url: https://github.com/tensorflow/tensorflow
author: Mihai Maruseac
author_date: 2021-07-27 15:20:26-07:00
msg: Prevent heap OOB read in TFLite's `gather_nd.cc`.

Passing negative indices is illegal but there was a missing check so that resulted in OOB accesses.

PiperOrigin-RevId: 387208551
Change-Id: I6b7a8a62d3e7c13a16d81619e5bc23ae2cdbc7fd
repository: repo_url: https://github.com/tensorflow/tensorflow
repo_name: tensorflow/tensorflow
description: An Open Source Machine Learning Framework for Everyone
repo_language: C++
owner: tensorflow
file_changes: filename: gather_nd.cc
change_type: ModificationType.MODIFY
diff: @@ -123,6 +123,17 @@ TfLiteStatus GatherNdString(const TfLiteTensor* params,
 template <typename IndicesT>
 TfLiteStatus EvalGatherNd(TfLiteContext* context, const TfLiteTensor* params,
                           const TfLiteTensor* indices, TfLiteTensor* output) {
+  bool indices_has_only_positive_elements = true;
+  const auto* indices_values = GetTensorData<IndicesT>(indices);
+  const size_t num_indices = indices->bytes / sizeof(IndicesT);
+  for (size_t i = 0; i < num_indices; i++) {
+    if (indices_values[i] < 0) {
+      indices_has_only_positive_elements = false;
+      break;
+    }
+  }
+  TF_LITE_ENSURE(context, indices_has_only_positive_elements);
+
   switch (params->type) {
     case kTfLiteFloat32:
       return GatherNd<float, IndicesT>(params, indices, output);

programming_language: Objective-C