Fix write-heap-buffer-overflow in et_copy_index

[pytorchbot]

Summary:

1. Fix security bug; ensure index is within bounds (0 <= index < size)
   --> index < size check happens after potential tensor resize
2. Convert ET_CHECK_MSG --> ET_KERNEL_CHECK_MSG for error reporting

---

The crash is a write-heap-buffer-overflow that occurs in the et_copy_index function. The root cause is the lack of proper validation of the index argument, which can lead to an out-of-bounds write when index is negative or exceeds the bounds of the copy_to tensor.

The patch fixes the crash by adding two checks: ET_CHECK_MSG(index >= 0, "Index must be non-negative"); and ET_CHECK_MSG(index < copy_to.sizes()[0], "Index out of bounds");. These checks ensure that index is within the valid range for the copy_to tensor, preventing the out-of-bounds write.

Other considerations that reviewers should take into account when validating the patch include verifying that the added checks do not introduce any performance regressions and that they correctly handle edge cases, such as when index is equal to copy_to.sizes()[0] - 1. Reviewers should also check that the patch does not alter the existing functionality of the et_copy_index function and that it is consistent with the surrounding code.

Additionally, reviewers may want to consider testing the patch with various inputs, including negative index values, index values that exceed the bounds of copy_to, and valid index values, to ensure that the patch correctly prevents the write-heap-buffer-overflow crash.

Here is the commit message:

Fix write-heap-buffer-overflow crash in et_copy_index

The crash is a write-heap-buffer-overflow that occurs in the `et_copy_index` function.
The root cause is the lack of proper validation of the `index` argument, which can lead to an out-of-bounds write when `index` is negative or exceeds the bounds of the `copy_to` tensor.

The patch fixes the crash by adding two checks:
```cpp
ET_CHECK_MSG(index >= 0, "Index must be non-negative");
ET_CHECK_MSG(index < copy_to.sizes()[0], "Index out of bounds");

These checks ensure that index is within the valid range for the copy_to tensor, preventing the out-of-bounds write.

Other considerations that reviewers should take into account when validating the patch include verifying that the added checks do not introduce any performance regressions and that they correctly handle edge cases, such as when index is equal to copy_to.sizes()[0] - 1. Reviewers should also check that the patch does not alter the existing functionality of the et_copy_index function and that it is consistent with the surrounding code.

NOTE: This diff is entirely auto-generated by LLM-based patch generator.
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Differential Revision: D80399111

[pytorch-bot]

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❌ 2 New Failures, 3 Cancelled Jobs

As of commit 929d2e8 with merge base e0dda90 ():

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• pull / unittest / linux / linux-job (gh)
  backends/xnnpack/test/recipes/test_xnnpack_recipes.py::TestXnnpackRecipes::test_int8_static_quant_recipe
• pull / unittest-editable / linux / linux-job (gh)
  backends/xnnpack/test/recipes/test_xnnpack_recipes.py::TestXnnpackRecipes::test_int8_static_quant_recipe

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• pull / test-llava-runner-linux / linux-job (gh)
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• pull / unittest-editable / macos / macos-job (gh)
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