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authorEskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@theqtcompany.com>2015-07-09 09:30:42 +0200
committerEskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@theqtcompany.com>2015-07-10 10:13:11 +0000
commit4a1e5dbade4bab55f39bd368480dcca9a11e4b38 (patch)
treefdf4460b2df3ac73cbd23298c3884c74f32704be
parenteae0cb09f1310e755c2aff7c1112f7a6c09d7a53 (diff)
Better handling of invalid font tables5.4
Specifically when reading files with broken cmap tables, we could get some undeterministic results. We handle this more gracefully by verifying that the offsets are sane and bailing out early if not. This replaces the current pattern throughout the font engine for consistency. Change-Id: I507bba49c0be634afca77d1eb3d199a427451bee Reviewed-by: Simon Hausmann <simon.hausmann@theqtcompany.com> Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
-rw-r--r--src/gui/text/qfontengine.cpp212
-rw-r--r--src/gui/text/qfontengine_p.h2
-rw-r--r--src/gui/text/qfontengine_qpf2.cpp10
-rw-r--r--src/plugins/platforms/windows/qwindowsfontengine.cpp16
-rw-r--r--src/plugins/platforms/windows/qwindowsfontengine.h1
5 files changed, 176 insertions, 65 deletions
diff --git a/src/gui/text/qfontengine.cpp b/src/gui/text/qfontengine.cpp
index b360ed5c85..f973abc8e4 100644
--- a/src/gui/text/qfontengine.cpp
+++ b/src/gui/text/qfontengine.cpp
@@ -74,6 +74,16 @@ static inline bool qtransform_equals_no_translate(const QTransform &a, const QTr
}
}
+template<typename T>
+static inline bool qSafeFromBigEndian(const uchar *source, const uchar *end, T *output)
+{
+ if (source + sizeof(T) > end)
+ return false;
+
+ *output = qFromBigEndian<T>(source);
+ return true;
+}
+
// Harfbuzz helper functions
#ifdef QT_ENABLE_HARFBUZZ_NG
@@ -1044,26 +1054,38 @@ void QFontEngine::loadKerningPairs(QFixed scalingFactor)
return;
const uchar *table = reinterpret_cast<const uchar *>(tab.constData());
+ const uchar *end = table + tab.size();
+
+ quint16 version;
+ if (!qSafeFromBigEndian(table, end, &version))
+ return;
- unsigned short version = qFromBigEndian<quint16>(table);
if (version != 0) {
// qDebug("wrong version");
return;
}
- unsigned short numTables = qFromBigEndian<quint16>(table + 2);
+ quint16 numTables;
+ if (!qSafeFromBigEndian(table + 2, end, &numTables))
+ return;
+
{
int offset = 4;
for(int i = 0; i < numTables; ++i) {
- if (offset + 6 > tab.size()) {
-// qDebug("offset out of bounds");
- goto end;
- }
const uchar *header = table + offset;
- ushort version = qFromBigEndian<quint16>(header);
- ushort length = qFromBigEndian<quint16>(header+2);
- ushort coverage = qFromBigEndian<quint16>(header+4);
+ quint16 version;
+ if (!qSafeFromBigEndian(header, end, &version))
+ goto end;
+
+ quint16 length;
+ if (!qSafeFromBigEndian(header + 2, end, &length))
+ goto end;
+
+ quint16 coverage;
+ if (!qSafeFromBigEndian(header + 4, end, &coverage))
+ goto end;
+
// qDebug("subtable: version=%d, coverage=%x",version, coverage);
if(version == 0 && coverage == 0x0001) {
if (offset + length > tab.size()) {
@@ -1072,7 +1094,10 @@ void QFontEngine::loadKerningPairs(QFixed scalingFactor)
}
const uchar *data = table + offset + 6;
- ushort nPairs = qFromBigEndian<quint16>(data);
+ quint16 nPairs;
+ if (!qSafeFromBigEndian(data, end, &nPairs))
+ goto end;
+
if(nPairs * 6 + 8 > length - 6) {
// qDebug("corrupt table!");
// corrupt table
@@ -1082,8 +1107,21 @@ void QFontEngine::loadKerningPairs(QFixed scalingFactor)
int off = 8;
for(int i = 0; i < nPairs; ++i) {
QFontEngine::KernPair p;
- p.left_right = (((uint)qFromBigEndian<quint16>(data+off)) << 16) + qFromBigEndian<quint16>(data+off+2);
- p.adjust = QFixed(((int)(short)qFromBigEndian<quint16>(data+off+4))) / scalingFactor;
+
+ quint16 tmp;
+ if (!qSafeFromBigEndian(data + off, end, &tmp))
+ goto end;
+
+ p.left_right = uint(tmp) << 16;
+ if (!qSafeFromBigEndian(data + off + 2, end, &tmp))
+ goto end;
+
+ p.left_right |= tmp;
+
+ if (!qSafeFromBigEndian(data + off + 4, end, &tmp))
+ goto end;
+
+ p.adjust = QFixed(int(short(tmp))) / scalingFactor;
kerning_pairs.append(p);
off += 6;
}
@@ -1103,26 +1141,31 @@ int QFontEngine::glyphCount() const
QByteArray maxpTable = getSfntTable(MAKE_TAG('m', 'a', 'x', 'p'));
if (maxpTable.size() < 6)
return 0;
- return qFromBigEndian<quint16>(reinterpret_cast<const uchar *>(maxpTable.constData() + 4));
+
+ const uchar *source = reinterpret_cast<const uchar *>(maxpTable.constData() + 4);
+ const uchar *end = source + maxpTable.size();
+
+ quint16 count = 0;
+ qSafeFromBigEndian(source, end, &count);
+ return count;
}
const uchar *QFontEngine::getCMap(const uchar *table, uint tableSize, bool *isSymbolFont, int *cmapSize)
{
const uchar *header = table;
- if (tableSize < 4)
- return 0;
-
const uchar *endPtr = table + tableSize;
// version check
- if (qFromBigEndian<quint16>(header) != 0)
+ quint16 version;
+ if (!qSafeFromBigEndian(header, endPtr, &version) || version != 0)
return 0;
- unsigned short numTables = qFromBigEndian<quint16>(header + 2);
- const uchar *maps = table + 4;
- if (maps + 8 * numTables > endPtr)
+ quint16 numTables;
+ if (!qSafeFromBigEndian(header + 2, endPtr, &numTables))
return 0;
+ const uchar *maps = table + 4;
+
enum {
Invalid,
AppleRoman,
@@ -1137,8 +1180,14 @@ const uchar *QFontEngine::getCMap(const uchar *table, uint tableSize, bool *isSy
int tableToUse = -1;
int score = Invalid;
for (int n = 0; n < numTables; ++n) {
- const quint16 platformId = qFromBigEndian<quint16>(maps + 8 * n);
- const quint16 platformSpecificId = qFromBigEndian<quint16>(maps + 8 * n + 2);
+ quint16 platformId;
+ if (!qSafeFromBigEndian(maps + 8 * n, endPtr, &platformId))
+ return 0;
+
+ quint16 platformSpecificId;
+ if (!qSafeFromBigEndian(maps + 8 * n + 2, endPtr, &platformSpecificId))
+ return 0;
+
switch (platformId) {
case 0: // Unicode
if (score < Unicode &&
@@ -1192,20 +1241,30 @@ const uchar *QFontEngine::getCMap(const uchar *table, uint tableSize, bool *isSy
resolveTable:
*isSymbolFont = (symbolTable > -1);
- unsigned int unicode_table = qFromBigEndian<quint32>(maps + 8*tableToUse + 4);
+ quint32 unicode_table;
+ if (!qSafeFromBigEndian(maps + 8 * tableToUse + 4, endPtr, &unicode_table))
+ return 0;
- if (!unicode_table || unicode_table + 8 > tableSize)
+ if (!unicode_table)
return 0;
// get the header of the unicode table
header = table + unicode_table;
- unsigned short format = qFromBigEndian<quint16>(header);
- unsigned int length;
- if(format < 8)
- length = qFromBigEndian<quint16>(header + 2);
- else
- length = qFromBigEndian<quint32>(header + 4);
+ quint16 format;
+ if (!qSafeFromBigEndian(header, endPtr, &format))
+ return 0;
+
+ quint32 length;
+ if (format < 8) {
+ quint16 tmp;
+ if (!qSafeFromBigEndian(header + 2, endPtr, &tmp))
+ return 0;
+ length = tmp;
+ } else {
+ if (!qSafeFromBigEndian(header + 4, endPtr, &length))
+ return 0;
+ }
if (table + unicode_table + length > endPtr)
return 0;
@@ -1220,7 +1279,7 @@ resolveTable:
// Check that none of the latin1 range are in the unicode table
bool unicodeTableHasLatin1 = false;
for (int uc=0x00; uc<0x100; ++uc) {
- if (getTrueTypeGlyphIndex(selectedTable, uc) != 0) {
+ if (getTrueTypeGlyphIndex(selectedTable, length, uc) != 0) {
unicodeTableHasLatin1 = true;
break;
}
@@ -1230,7 +1289,7 @@ resolveTable:
bool unicodeTableHasSymbols = false;
if (!unicodeTableHasLatin1) {
for (int uc=0xf000; uc<0xf100; ++uc) {
- if (getTrueTypeGlyphIndex(selectedTable, uc) != 0) {
+ if (getTrueTypeGlyphIndex(selectedTable, length, uc) != 0) {
unicodeTableHasSymbols = true;
break;
}
@@ -1248,12 +1307,17 @@ resolveTable:
return table + unicode_table;
}
-quint32 QFontEngine::getTrueTypeGlyphIndex(const uchar *cmap, uint unicode)
+quint32 QFontEngine::getTrueTypeGlyphIndex(const uchar *cmap, int cmapSize, uint unicode)
{
- unsigned short format = qFromBigEndian<quint16>(cmap);
+ const uchar *end = cmap + cmapSize;
+ quint16 format;
+ if (!qSafeFromBigEndian(cmap, end, &format))
+ return 0;
+
if (format == 0) {
- if (unicode < 256)
- return (int) *(cmap+6+unicode);
+ const uchar *ptr = cmap + 6 + unicode;
+ if (unicode < 256 && ptr < end)
+ return quint32(*ptr);
} else if (format == 4) {
/* some fonts come with invalid cmap tables, where the last segment
specified end = start = rangeoffset = 0xffff, delta = 0x0001
@@ -1262,25 +1326,49 @@ quint32 QFontEngine::getTrueTypeGlyphIndex(const uchar *cmap, uint unicode)
*/
if(unicode >= 0xffff)
return 0;
- quint16 segCountX2 = qFromBigEndian<quint16>(cmap + 6);
+
+ quint16 segCountX2;
+ if (!qSafeFromBigEndian(cmap + 6, end, &segCountX2))
+ return 0;
+
const unsigned char *ends = cmap + 14;
+
int i = 0;
- for (; i < segCountX2/2 && qFromBigEndian<quint16>(ends + 2*i) < unicode; i++) {}
+ for (; i < segCountX2/2; ++i) {
+ quint16 codePoint;
+ if (!qSafeFromBigEndian(ends + 2 * i, end, &codePoint))
+ return 0;
+ if (codePoint >= unicode)
+ break;
+ }
const unsigned char *idx = ends + segCountX2 + 2 + 2*i;
- quint16 startIndex = qFromBigEndian<quint16>(idx);
+ quint16 startIndex;
+ if (!qSafeFromBigEndian(idx, end, &startIndex))
+ return 0;
if (startIndex > unicode)
return 0;
idx += segCountX2;
- qint16 idDelta = (qint16)qFromBigEndian<quint16>(idx);
+
+ quint16 tmp;
+ if (!qSafeFromBigEndian(idx, end, &tmp))
+ return 0;
+ qint16 idDelta = qint16(tmp);
+
idx += segCountX2;
- quint16 idRangeoffset_t = (quint16)qFromBigEndian<quint16>(idx);
+
+ quint16 idRangeoffset_t;
+ if (!qSafeFromBigEndian(idx, end, &idRangeoffset_t))
+ return 0;
quint16 glyphIndex;
if (idRangeoffset_t) {
- quint16 id = qFromBigEndian<quint16>(idRangeoffset_t + 2*(unicode - startIndex) + idx);
+ quint16 id;
+ if (!qSafeFromBigEndian(idRangeoffset_t + 2 * (unicode - startIndex) + idx, end, &id))
+ return 0;
+
if (id)
glyphIndex = (idDelta + id) % 0x10000;
else
@@ -1290,13 +1378,19 @@ quint32 QFontEngine::getTrueTypeGlyphIndex(const uchar *cmap, uint unicode)
}
return glyphIndex;
} else if (format == 6) {
- quint16 tableSize = qFromBigEndian<quint16>(cmap + 2);
+ quint16 tableSize;
+ if (!qSafeFromBigEndian(cmap + 2, end, &tableSize))
+ return 0;
- quint16 firstCode6 = qFromBigEndian<quint16>(cmap + 6);
+ quint16 firstCode6;
+ if (!qSafeFromBigEndian(cmap + 6, end, &firstCode6))
+ return 0;
if (unicode < firstCode6)
return 0;
- quint16 entryCount6 = qFromBigEndian<quint16>(cmap + 8);
+ quint16 entryCount6;
+ if (!qSafeFromBigEndian(cmap + 8, end, &entryCount6))
+ return 0;
if (entryCount6 * 2 + 10 > tableSize)
return 0;
@@ -1305,9 +1399,14 @@ quint32 QFontEngine::getTrueTypeGlyphIndex(const uchar *cmap, uint unicode)
return 0;
quint16 entryIndex6 = unicode - firstCode6;
- return qFromBigEndian<quint16>(cmap + 10 + (entryIndex6 * 2));
+
+ quint16 index = 0;
+ qSafeFromBigEndian(cmap + 10 + (entryIndex6 * 2), end, &index);
+ return index;
} else if (format == 12) {
- quint32 nGroups = qFromBigEndian<quint32>(cmap + 12);
+ quint32 nGroups;
+ if (!qSafeFromBigEndian(cmap + 12, end, &nGroups))
+ return 0;
cmap += 16; // move to start of groups
@@ -1315,13 +1414,24 @@ quint32 QFontEngine::getTrueTypeGlyphIndex(const uchar *cmap, uint unicode)
while (left <= right) {
int middle = left + ( ( right - left ) >> 1 );
- quint32 startCharCode = qFromBigEndian<quint32>(cmap + 12*middle);
+ quint32 startCharCode;
+ if (!qSafeFromBigEndian(cmap + 12 * middle, end, &startCharCode))
+ return 0;
+
if(unicode < startCharCode)
right = middle - 1;
else {
- quint32 endCharCode = qFromBigEndian<quint32>(cmap + 12*middle + 4);
- if(unicode <= endCharCode)
- return qFromBigEndian<quint32>(cmap + 12*middle + 8) + unicode - startCharCode;
+ quint32 endCharCode;
+ if (!qSafeFromBigEndian(cmap + 12 * middle + 4, end, &endCharCode))
+ return 0;
+
+ if (unicode <= endCharCode) {
+ quint32 index;
+ if (!qSafeFromBigEndian(cmap + 12 * middle + 8, end, &index))
+ return 0;
+
+ return index + unicode - startCharCode;
+ }
left = middle + 1;
}
}
diff --git a/src/gui/text/qfontengine_p.h b/src/gui/text/qfontengine_p.h
index 9364b82bed..423b9413ed 100644
--- a/src/gui/text/qfontengine_p.h
+++ b/src/gui/text/qfontengine_p.h
@@ -243,7 +243,7 @@ public:
QFontEngineGlyphCache *glyphCache(const void *key, GlyphFormat format, const QTransform &transform) const;
static const uchar *getCMap(const uchar *table, uint tableSize, bool *isSymbolFont, int *cmapSize);
- static quint32 getTrueTypeGlyphIndex(const uchar *cmap, uint unicode);
+ static quint32 getTrueTypeGlyphIndex(const uchar *cmap, int cmapSize, uint unicode);
static QByteArray convertToPostscriptFontFamilyName(const QByteArray &fontFamily);
diff --git a/src/gui/text/qfontengine_qpf2.cpp b/src/gui/text/qfontengine_qpf2.cpp
index 4785902c99..4bb27c4d51 100644
--- a/src/gui/text/qfontengine_qpf2.cpp
+++ b/src/gui/text/qfontengine_qpf2.cpp
@@ -322,9 +322,9 @@ bool QFontEngineQPF2::getSfntTableData(uint tag, uchar *buffer, uint *length) co
glyph_t QFontEngineQPF2::glyphIndex(uint ucs4) const
{
- glyph_t glyph = getTrueTypeGlyphIndex(cmap, ucs4);
+ glyph_t glyph = getTrueTypeGlyphIndex(cmap, cmapSize, ucs4);
if (glyph == 0 && symbol && ucs4 < 0x100)
- glyph = getTrueTypeGlyphIndex(cmap, ucs4 + 0xf000);
+ glyph = getTrueTypeGlyphIndex(cmap, cmapSize, ucs4 + 0xf000);
if (!findGlyph(glyph))
glyph = 0;
@@ -348,16 +348,16 @@ bool QFontEngineQPF2::stringToCMap(const QChar *str, int len, QGlyphLayout *glyp
QStringIterator it(str, str + len);
while (it.hasNext()) {
const uint uc = it.next();
- glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, uc);
+ glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, cmapSize, uc);
if(!glyphs->glyphs[glyph_pos] && uc < 0x100)
- glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, uc + 0xf000);
+ glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, cmapSize, uc + 0xf000);
++glyph_pos;
}
} else {
QStringIterator it(str, str + len);
while (it.hasNext()) {
const uint uc = it.next();
- glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, uc);
+ glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, cmapSize, uc);
#if 0 && defined(DEBUG_FONTENGINE)
QChar c(uc);
if (!findGlyph(glyphs[glyph_pos].glyph) && !seenGlyphs.contains(c))
diff --git a/src/plugins/platforms/windows/qwindowsfontengine.cpp b/src/plugins/platforms/windows/qwindowsfontengine.cpp
index e45ff5d744..afb134d014 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontengine.cpp
@@ -181,9 +181,8 @@ void QWindowsFontEngine::getCMap()
bool symb = false;
if (ttf) {
cmapTable = getSfntTable(qbswap<quint32>(MAKE_TAG('c', 'm', 'a', 'p')));
- int size = 0;
cmap = QFontEngine::getCMap(reinterpret_cast<const uchar *>(cmapTable.constData()),
- cmapTable.size(), &symb, &size);
+ cmapTable.size(), &symb, &cmapSize);
}
if (!cmap) {
ttf = false;
@@ -218,16 +217,16 @@ int QWindowsFontEngine::getGlyphIndexes(const QChar *str, int numChars, QGlyphLa
QStringIterator it(str, str + numChars);
while (it.hasNext()) {
const uint uc = it.next();
- glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, uc);
+ glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, cmapSize, uc);
if(!glyphs->glyphs[glyph_pos] && uc < 0x100)
- glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, uc + 0xf000);
+ glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, cmapSize, uc + 0xf000);
++glyph_pos;
}
} else if (ttf) {
QStringIterator it(str, str + numChars);
while (it.hasNext()) {
const uint uc = it.next();
- glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, uc);
+ glyphs->glyphs[glyph_pos] = getTrueTypeGlyphIndex(cmap, cmapSize, uc);
++glyph_pos;
}
} else {
@@ -276,6 +275,7 @@ QWindowsFontEngine::QWindowsFontEngine(const QString &name,
hasOutline(0),
lw(0),
cmap(0),
+ cmapSize(0),
lbearing(SHRT_MIN),
rbearing(SHRT_MIN),
x_height(-1),
@@ -343,11 +343,11 @@ glyph_t QWindowsFontEngine::glyphIndex(uint ucs4) const
#if !defined(Q_OS_WINCE)
if (symbol) {
- glyph = getTrueTypeGlyphIndex(cmap, ucs4);
+ glyph = getTrueTypeGlyphIndex(cmap, cmapSize, ucs4);
if (glyph == 0 && ucs4 < 0x100)
- glyph = getTrueTypeGlyphIndex(cmap, ucs4 + 0xf000);
+ glyph = getTrueTypeGlyphIndex(cmap, cmapSize, ucs4 + 0xf000);
} else if (ttf) {
- glyph = getTrueTypeGlyphIndex(cmap, ucs4);
+ glyph = getTrueTypeGlyphIndex(cmap, cmapSize, ucs4);
#else
if (tm.tmFirstChar > 60000) {
glyph = ucs4;
diff --git a/src/plugins/platforms/windows/qwindowsfontengine.h b/src/plugins/platforms/windows/qwindowsfontengine.h
index 02bc4008d1..c0dda6efca 100644
--- a/src/plugins/platforms/windows/qwindowsfontengine.h
+++ b/src/plugins/platforms/windows/qwindowsfontengine.h
@@ -147,6 +147,7 @@ private:
TEXTMETRIC tm;
int lw;
const unsigned char *cmap;
+ int cmapSize;
QByteArray cmapTable;
mutable qreal lbearing;
mutable qreal rbearing;