qt5-qtdeclarative/0014-QSGOpenGLDistanceFieldGlyphCache-fix-UB-ordering-of-.patch

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From 985358efb1e60a8ff493da4d6ca9056f63dc9982 Mon Sep 17 00:00:00 2001
From: Marc Mutz <marc.mutz@kdab.com>
Date: Tue, 16 Jul 2019 11:31:01 +0200
Subject: [PATCH 14/18] QSGOpenGLDistanceFieldGlyphCache: fix UB (ordering of
pointers not from the same array)
The code performed out of bounds checks by adding the size of the
buffer to a pointer and comparing the result to the the
one-past-the-end pointer of the buffer.
This is UB, for three reasons:
- in one case, a qint64 is added to a pointer, silently truncating the
result on 32bit platforms
- if the buffer overflow is large, the pointer value may wrap around,
yielding a result that is numerically less than the end pointer, but
still out-of-bounds.
- pointer order is only defined within a C array, plus one past the
end. On failure, pointers outside that range are compared.
Fix by comparing distance(it, end) with the required size for the
chunk to be written instead.
Pick-to: 6.3 6.2 5.15
Change-Id: I356bb8c8a65a93b8b1c1eb7bac381dd64bea719e
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 8d9bd6b381bfc759d575954801b683354ad6a790)
---
src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp b/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp
index f7cb8bede3..219cdd5966 100644
--- a/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp
+++ b/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp
@@ -446,7 +446,7 @@ bool QSGRhiDistanceFieldGlyphCache::loadPregeneratedCache(const QRawFont &font)
const char *textureRecord = allocatorData;
for (int i = 0; i < textureCount; ++i, textureRecord += Qtdf::TextureRecordSize) {
- if (textureRecord + Qtdf::TextureRecordSize > qtdfTableEnd) {
+ if (qtdfTableEnd - textureRecord < Qtdf::TextureRecordSize) {
qWarning("qtdf table too small in font '%s'.",
qPrintable(font.familyName()));
return false;
@@ -462,7 +462,7 @@ bool QSGRhiDistanceFieldGlyphCache::loadPregeneratedCache(const QRawFont &font)
const char *glyphRecord = textureRecord;
for (quint32 i = 0; i < glyphCount; ++i, glyphRecord += Qtdf::GlyphRecordSize) {
- if (glyphRecord + Qtdf::GlyphRecordSize > qtdfTableEnd) {
+ if (qtdfTableEnd - glyphRecord < Qtdf:: GlyphRecordSize) {
qWarning("qtdf table too small in font '%s'.",
qPrintable(font.familyName()));
return false;
@@ -513,7 +513,7 @@ bool QSGRhiDistanceFieldGlyphCache::loadPregeneratedCache(const QRawFont &font)
int width = texInfo->allocatedArea.width();
int height = texInfo->allocatedArea.height();
qint64 size = qint64(width) * height;
- if (reinterpret_cast<const char *>(textureData + size) > qtdfTableEnd) {
+ if (qtdfTableEnd - reinterpret_cast<const char *>(textureData) < size) {
qWarning("qtdf table too small in font '%s'.",
qPrintable(font.familyName()));
return false;
--
2.37.3