diff options
author | Marc Mutz <marc.mutz@kdab.com> | 2019-07-16 11:31:01 +0200 |
---|---|---|
committer | Qt Cherry-pick Bot <cherrypick_bot@qt-project.org> | 2022-03-19 11:25:27 +0000 |
commit | a5635345175e667601c8b6a344508c4d4ebb0f9d (patch) | |
tree | 9688b3052eb5d022793bd512a17a554e0332669e | |
parent | ed41fb59cad2fabc9b9382c703d16cec8f904acd (diff) |
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.
Change-Id: I356bb8c8a65a93b8b1c1eb7bac381dd64bea719e
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
(cherry picked from commit 8d9bd6b381bfc759d575954801b683354ad6a790)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>
-rw-r--r-- | src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp b/src/quick/scenegraph/qsgrhidistancefieldglyphcache.cpp index 23e6de51a9..c368661505 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; |