Merge pull request #75266 from swiftlang/susmonteiro/cxx-precondition-oob

susmonteiro · web-flow · commit e2a0be85c5af · 2024-07-18T18:28:23.000+01:00
Add precondition to prevent out-of-bounds access
diff --git a/stdlib/public/Cxx/CxxRandomAccessCollection.swift b/stdlib/public/Cxx/CxxRandomAccessCollection.swift
@@ -44,6 +44,7 @@ extension CxxRandomAccessCollection {
       // Not using CxxIterator here to avoid making a copy of the collection.
       var rawIterator = __beginUnsafe()
       rawIterator += RawIterator.Distance(index)
+      precondition(__endUnsafe() - rawIterator > 0, "C++ iterator access out of bounds")  
       yield rawIterator.pointee
     }
   }

Original file line number	Diff line number	Diff line change
`@@ -44,6 +44,7 @@ extension CxxRandomAccessCollection {`
`44`	`44`	`// Not using CxxIterator here to avoid making a copy of the collection.`
`45`	`45`	`var rawIterator = __beginUnsafe()`
`46`	`46`	`rawIterator += RawIterator.Distance(index)`
	`47`	`+ precondition(__endUnsafe() - rawIterator > 0, "C++ iterator access out of bounds")`
`47`	`48`	`yield rawIterator.pointee`
`48`	`49`	`}`
`49`	`50`	`}`