helper package functions to copy maps/slices encourage unsafe usage
#11564
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tgross
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In the system scheduler, if a subset of clients are filtered by class, we hit a code path where the `AllocMetric` has been copied, but the `Copy` method does not instantiate the various maps. This leads to an assignment to a nil map. This changeset ensures that the maps are non-nil before continuing. The `Copy` method relies on functions in the `helper` package that all return nil slices or maps when passed zero-length inputs. This changeset to fix the panic bug intentionally defers updating those functions because it'll have potential impact on memory usage. See #11564 for more details.
tgross
added a commit
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Nov 24, 2021
) In the system scheduler, if a subset of clients are filtered by class, we hit a code path where the `AllocMetric` has been copied, but the `Copy` method does not instantiate the various maps. This leads to an assignment to a nil map. This changeset ensures that the maps are non-nil before continuing. The `Copy` method relies on functions in the `helper` package that all return nil slices or maps when passed zero-length inputs. This changeset to fix the panic bug intentionally defers updating those functions because it'll have potential impact on memory usage. See #11564 for more details.
lgfa29
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Nov 24, 2021
) In the system scheduler, if a subset of clients are filtered by class, we hit a code path where the `AllocMetric` has been copied, but the `Copy` method does not instantiate the various maps. This leads to an assignment to a nil map. This changeset ensures that the maps are non-nil before continuing. The `Copy` method relies on functions in the `helper` package that all return nil slices or maps when passed zero-length inputs. This changeset to fix the panic bug intentionally defers updating those functions because it'll have potential impact on memory usage. See #11564 for more details.
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Fixed by #14139 |
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The various generic copy helper functions in the
helperpackage returnnilif the input is zero-length. This was likely done to save memory by avoiding heap-allocating empty maps and slices (a few pointers each). But this encourages usage wherenilmaps are being passed around and need to be checked everywhere after a copy, or we can hit a panic. See #11563 (comment) for an example.The functions have a lot of callers, so one approach we might want to consider here is having the
Copymethods in thenomad/structspackage use new variants that allocate the empty map.The text was updated successfully, but these errors were encountered: