Vulnerability: Heap OOB and CHECK fail in `ResourceGather` ### Impact
An attacker can trigger a crash via a `CHECK`-fail in debug builds of TensorFlow using `tf.raw_ops.ResourceGather` or a read from outside the bounds of heap allocated data in the same API in a release build:

```python
import tensorflow as tf

tensor = tf.constant(value=[[1,2],[3,4],[5,6]],shape=(3,2),dtype=tf.uint32)
v = tf.Variable(tensor)
tf.raw_ops.ResourceGather(
  resource=v.handle,
  indices=[0],
  dtype=tf.uint32,
  batch_dims=10,
  validate_indices=False)
```

The [implementation](https://github.com/tensorflow/tensorflow/blob/f24faa153ad31a4b51578f8181d3aaab77a1ddeb/tensorflow/core/kernels/resource_variable_ops.cc#L660-L668) does not check that the `batch_dims` value that the user supplies is less than the rank of the input tensor.

Since the implementation uses several for loops over the dimensions of `tensor`, this results in reading data from outside the bounds of heap allocated buffer backing the tensor:

```cc
    // batch_dims_ = > params.dims() (10 > 2)
    for (int i = 0; i < batch_dims_; ++i) {
      result_shape.AddDim(params.dim_size(i));
    }
    for (int i = batch_dims_; i < indices.dims(); ++i) {
      result_shape.AddDim(indices.dim_size(i));
    }
    for (int i = batch_dims_ + 1; i < params.dims(); ++i) {
      result_shape.AddDim(params.dim_size(i));
    }
```

In debug mode, `.dim_size(i)` validates that the argument is less than `.dims()` using a `DCHECK`. But the `DCHECK` is a no-op in release builds.

### Patches
We have patched the issue in GitHub commit [bc9c546ce7015c57c2f15c168b3d9201de679a1d](https://github.com/tensorflow/tensorflow/commit/bc9c546ce7015c57c2f15c168b3d9201de679a1d).

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.

### For more information
Please consult [our security guide](https://github.com/tensorflow/tensorflow/blob/master/SECURITY.md) for more information regarding the security model and how to contact us with issues and questions.

### Attribution
This vulnerability has been reported by members of the Aivul Team from Qihoo 360.
Vulnerability ID: GHSA-2r8p-fg3c-wcj4
CWE: CWE-125
Severity score: 7.3
Project: https://github.com/tensorflow/tensorflow
Published: 2021-08-25
File: tensorflow/core/kernels/resource_variable_ops.cc
Commit message: Prevent heap oob access in `resource_variable_ops.cc`

PiperOrigin-RevId: 387936433
Change-Id: I9e71ddaa8dbd51ec6afbf163a6b3b591f193b4f6
Commit author: Mihai Maruseac

Vulnerable version (before fix):
 class ResourceGatherOp : public OpKernel {     OP_REQUIRES(         c, TensorShapeUtils::IsVectorOrHigher(params.shape()),         errors::InvalidArgument("params must be at least 1 dimensional"));      // Check that we have enough index space     const int64_t N = indices.NumElements();

Fixed version (after fix):
 class ResourceGatherOp : public OpKernel {     OP_REQUIRES(         c, TensorShapeUtils::IsVectorOrHigher(params.shape()),         errors::InvalidArgument("params must be at least 1 dimensional"));     OP_REQUIRES(         c, params.shape().dims() >= batch_dims_,         errors::InvalidArgument("params must have at least ", batch_dims_,                                 " (batch_dims) dimensions but it has shape ",                                 params.shape().DebugString()));      // Check that we have enough index space     const int64_t N = indices.NumElements();

Patch:
patch: @@ -660,6 +660,11 @@ class ResourceGatherOp : public OpKernel {
     OP_REQUIRES(
         c, TensorShapeUtils::IsVectorOrHigher(params.shape()),
         errors::InvalidArgument("params must be at least 1 dimensional"));
+    OP_REQUIRES(
+        c, params.shape().dims() >= batch_dims_,
+        errors::InvalidArgument("params must have at least ", batch_dims_,
+                                " (batch_dims) dimensions but it has shape ",
+                                params.shape().DebugString()));
 
     // Check that we have enough index space
     const int64_t N = indices.NumElements();
path: tensorflow/core/kernels/resource_variable_ops.cc