QVarLengthArray: protect against aliasing in resize(n, t)

Amends a00a1d8806cfbf17e04b88d1b4ff4a9cf5b6294a.

Pick-to: 6.5 6.4
Change-Id: I3fa6183466715555530d4042006049e286897343
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>

1 files changed, 4 insertions, 0 deletions

diff --git a/src/corelib/tools/qvarlengtharray.h b/src/corelib/tools/qvarlengtharray.h
index 1ecab338cf..dc6e88e3e8 100644
--- a/src/corelib/tools/qvarlengtharray.h
+++ b/src/corelib/tools/qvarlengtharray.h
@@ -218,6 +218,10 @@ protected:
     void reallocate_impl(qsizetype prealloc, void *array, qsizetype size, qsizetype alloc);
     void resize_impl(qsizetype prealloc, void *array, qsizetype sz, const T &v)
     {
+        if (QtPrivate::q_points_into_range(&v, begin(), end())) {
+            resize_impl(prealloc, array, sz, T(v));
+            return;
+        }
         reallocate_impl(prealloc, array, sz, qMax(sz, capacity()));
         while (size() < sz) {
             q20::construct_at(data() + size(), v);