Fix memcheck error in groupby-tdigest get_scalar_minmax #9339
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davidwendt
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bug
nvdbaranec
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Sep 29, 2021
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How slim are the odds of this fix making it back into |
jrhemstad
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Sep 29, 2021
Codecov Report
@@ Coverage Diff @@
## branch-21.12 #9339 +/- ##
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- Coverage 10.79% 10.77% -0.02%
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Files 116 116
Lines 18869 19360 +491
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+ Hits 2036 2087 +51
- Misses 16833 17273 +440
Continue to review full report at Codecov.
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nvdbaranec
requested changes
Sep 29, 2021
nvdbaranec
approved these changes
Sep 29, 2021
nvdbaranec
requested changes
Sep 30, 2021
nvdbaranec
approved these changes
Sep 30, 2021
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@gpucibot merge |
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The groupby tdigest logic in the
get_scalar_minmaxwould access incorrect device memory when encountering an empty group. The index value calculated for a column element in an empty group would be off by -1. This was found running a cuda-memcheck (compute-sanitizer) with theAllNullsgtest. Here the first group is empty resulting an out-of-bounds read atcol.element<T>(-1).This PR adds a check for the empty group (
valid_count==0) to prevent reading the incorrect column row.