From 1616c71921b73b227f56ccb3f2c49a994ec23440 Mon Sep 17 00:00:00 2001 From: Allan Sandfeld Jensen Date: Thu, 23 Jul 2020 11:48:48 +0200 Subject: Fix buffer overflow in XBM parser Avoid parsing over the buffer limit, or interpreting non-hex as hex. This still leaves parsing of lines longer than 300 chars unreliable Change-Id: I1c57a7e530c4380f6f9040b2ec729ccd7dc7a5fb Reviewed-by: Robert Loehning Reviewed-by: Eirik Aavitsland (cherry picked from commit c562c1fc19629fb505acd0f6380604840b634211) Reviewed-by: Qt Cherry-pick Bot --- src/gui/image/qxbmhandler.cpp | 4 ++- .../gui/image/qimagereader/tst_qimagereader.cpp | 38 ++++++++++++++++++++++ 2 files changed, 41 insertions(+), 1 deletion(-) diff --git a/src/gui/image/qxbmhandler.cpp b/src/gui/image/qxbmhandler.cpp index f06561690c..72ce7f7ecd 100644 --- a/src/gui/image/qxbmhandler.cpp +++ b/src/gui/image/qxbmhandler.cpp @@ -159,7 +159,9 @@ static bool read_xbm_body(QIODevice *device, int w, int h, QImage *outImage) w = (w+7)/8; // byte width while (y < h) { // for all encoded bytes... - if (p) { // p = "0x.." + if (p && p < (buf + readBytes - 3)) { // p = "0x.." + if (!isxdigit(p[2]) || !isxdigit(p[3])) + return false; *b++ = hex2byte(p+2); p += 2; if (++x == w && ++y < h) { diff --git a/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp b/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp index cf8a0d1cff..984a7c7482 100644 --- a/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp +++ b/tests/auto/gui/image/qimagereader/tst_qimagereader.cpp @@ -175,6 +175,8 @@ private slots: void xpmBufferOverflow(); + void xbmBufferHandling(); + private: QString prefix; QTemporaryDir m_temporaryDir; @@ -2055,5 +2057,41 @@ void tst_QImageReader::xpmBufferOverflow() QImageReader(":/images/oss-fuzz-23988.xpm").read(); } +void tst_QImageReader::xbmBufferHandling() +{ + uint8_t original_buffer[256]; + for (int i = 0; i < 256; ++i) + original_buffer[i] = i; + + QImage image(original_buffer, 256, 8, QImage::Format_MonoLSB); + image.setColorTable({0xff000000, 0xffffffff}); + + QByteArray buffer; + { + QBuffer buf(&buffer); + QImageWriter writer(&buf, "xbm"); + writer.write(image); + } + + QCOMPARE(QImage::fromData(buffer, "xbm"), image); + + auto i = buffer.indexOf(','); + buffer.insert(i + 1, " "); + QCOMPARE(QImage::fromData(buffer, "xbm"), image); + buffer.insert(i + 1, " "); + QCOMPARE(QImage::fromData(buffer, "xbm"), image); + buffer.insert(i + 1, " "); +#if 0 // Lines longer than 300 chars not supported currently + QCOMPARE(QImage::fromData(buffer, "xbm"), image); +#endif + + i = buffer.lastIndexOf("\n "); + buffer.truncate(i + 1); + buffer.append(QByteArray(297, ' ')); + buffer.append("0x"); + // Only check we get no buffer overflow + QImage::fromData(buffer, "xbm"); +} + QTEST_MAIN(tst_QImageReader) #include "tst_qimagereader.moc" -- cgit v1.2.3