From 86a0e70d65f406359e36b1a0f714a8ff3e5394e1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?M=C3=A5rten=20Nordheim?= <marten.nordheim@qt.io>
Date: Tue, 25 Apr 2023 14:30:44 +0200
Subject: [PATCH] QDataBuffer: decrease size on shrink()

Having the size potentially be larger than the capacity can't
be considered anything other than a bug.

Pick-to: 6.5
Change-Id: Id059c0f2c7320f992d897011d7aa944c5cb86058
Reviewed-by: Laszlo Agocs <laszlo.agocs@qt.io>
---
 src/gui/painting/qdatabuffer_p.h | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/gui/painting/qdatabuffer_p.h b/src/gui/painting/qdatabuffer_p.h
index 1e62c8d924..8f467afe4e 100644
--- a/src/gui/painting/qdatabuffer_p.h
+++ b/src/gui/painting/qdatabuffer_p.h
@@ -89,13 +89,16 @@ public:
     }
 
     void shrink(qsizetype size) {
+        Q_ASSERT(capacity >= size);
         capacity = size;
         if (size) {
             buffer = (Type*) realloc(static_cast<void*>(buffer), capacity * sizeof(Type));
             Q_CHECK_PTR(buffer);
+            siz = std::min(siz, size);
         } else {
             free(buffer);
             buffer = nullptr;
+            siz = 0;
         }
     }