[llvm] [DebugInfo][DWARF] Bounds-check the unit-index parallel table (PR #213285)

[Matt Davis via llvm-commits]

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@@ -159,6 +159,8 @@ bool DWARFUnitIndex::parseImpl(DataExtractor IndexData) {
     auto Index = IndexData.getU32(&Offset);
     if (!Index)
       continue;
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enferex wrote:

I agree, the assumption of a `Contribs` with valid pointers feels wrong, and possibly a case where a malformed section could trigger a memory violation.

https://github.com/llvm/llvm-project/pull/213285