diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index aecd621..cbbd859 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -26,6 +26,7 @@ SET( LIBEXIV2_PRIVATE_HDR canonmn_int.hpp
pngchunk_int.hpp
rcsid_int.hpp
rw2image_int.hpp
+ safe_op.hpp
samsungmn_int.hpp
sigmamn_int.hpp
sonymn_int.hpp
@@ -102,6 +103,7 @@ SET( LIBEXIV2_SRC asfvideo.cpp
futils.cpp
fujimn.cpp
gifimage.cpp
+ helper_functions.cpp
http.cpp
image.cpp
ini.cpp
diff --git a/src/helper_functions.cpp b/src/helper_functions.cpp
new file mode 100644
index 0000000..623fbc1
--- /dev/null
+++ b/src/helper_functions.cpp
@@ -0,0 +1,39 @@
+// ********************************************************* -*- C++ -*-
+/*
+ * Copyright (C) 2004-2018 Exiv2 authors
+ *
+ * This program is part of the Exiv2 distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, 5th Floor, Boston, MA 02110-1301 USA.
+ */
+/*!
+ @file helper_functions.cpp
+ @brief A collection of helper functions
+ @author Dan Čermák (D4N)
+ <a href="mailto:dan.cermak@cgc-instruments.com">dan.cermak@cgc-instruments.com</a>
+ @date 25-May-18, D4N: created
+ */
+
+#include "helper_functions.hpp"
+
+#include <string.h>
+
+
+std::string string_from_unterminated(const char* data, size_t data_length)
+{
+ const size_t StringLength = strnlen(data, data_length);
+
+ return std::string(data, StringLength);
+}
diff --git a/src/helper_functions.hpp b/src/helper_functions.hpp
new file mode 100644
index 0000000..d70cbc1
--- /dev/null
+++ b/src/helper_functions.hpp
@@ -0,0 +1,50 @@
+// ********************************************************* -*- C++ -*-
+/*
+ * Copyright (C) 2004-2018 Exiv2 authors
+ *
+ * This program is part of the Exiv2 distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, 5th Floor, Boston, MA 02110-1301 USA.
+ */
+/*!
+ @file helper_functions.hpp
+ @brief A collection of helper functions
+ @author Dan Čermák (D4N)
+ <a href="mailto:dan.cermak@cgc-instruments.com">dan.cermak@cgc-instruments.com</a>
+ @date 25-May-18, D4N: created
+ */
+#ifndef HELPER_FUNCTIONS_HPP
+#define HELPER_FUNCTIONS_HPP
+
+#include <string>
+
+/*!
+ @brief Convert a (potentially not null terminated) array into a
+ std::string.
+
+ Convert a C style string that may or may not be null terminated safely
+ into a std::string. The string's termination is either set at the first \0
+ or after data_length characters.
+
+ @param[in] data A c-string from which the std::string shall be
+ constructed. Does not need to be null terminated.
+ @param[in] data_length An upper bound for the string length (must be at most
+ the allocated length of `buffer`). If no null terminator is found in data,
+ then the resulting std::string will be null terminated at `data_length`.
+
+ */
+std::string string_from_unterminated(const char* data, size_t data_length);
+
+#endif // HELPER_FUNCTIONS_HPP
diff --git a/src/pngchunk.cpp b/src/pngchunk.cpp
index 29ffcfa..e4e3274 100644
--- a/src/pngchunk.cpp
+++ b/src/pngchunk.cpp
@@ -38,6 +38,8 @@ EXIV2_RCSID("@(#) $Id$")
#include "image.hpp"
#include "error.hpp"
#include "enforce.hpp"
+#include "helper_functions.hpp"
+#include "safe_op.hpp"
// + standard includes
#include <sstream>
@@ -137,6 +139,8 @@ namespace Exiv2 {
if(type == zTXt_Chunk)
{
+ enforce(data.size_ >= Safe::add(keysize, 2), Exiv2::kerCorruptedMetadata);
+
// Extract a deflate compressed Latin-1 text chunk
// we get the compression method after the key
@@ -153,11 +157,13 @@ namespace Exiv2 {
// compressed string after the compression technique spec
const byte* compressedText = data.pData_ + keysize + 2;
unsigned int compressedTextSize = data.size_ - keysize - 2;
+ enforce(compressedTextSize < data.size_, kerCorruptedMetadata);
zlibUncompress(compressedText, compressedTextSize, arr);
}
else if(type == tEXt_Chunk)
{
+ enforce(data.size_ >= Safe::add(keysize, 1), Exiv2::kerCorruptedMetadata);
// Extract a non-compressed Latin-1 text chunk
// the text comes after the key, but isn't null terminated
@@ -168,6 +174,7 @@ namespace Exiv2 {
}
else if(type == iTXt_Chunk)
{
+ enforce(data.size_ >= Safe::add(keysize, 3), Exiv2::kerCorruptedMetadata);
const int nullSeparators = std::count(&data.pData_[keysize+3], &data.pData_[data.size_], '\0');
enforce(nullSeparators >= 2, Exiv2::kerCorruptedMetadata);
@@ -180,42 +187,46 @@ namespace Exiv2 {
const byte compressionMethod = data.pData_[keysize + 2];
enforce(compressionFlag == 0x00 || compressionFlag == 0x01, Exiv2::kerCorruptedMetadata);
enforce(compressionMethod == 0x00, Exiv2::kerCorruptedMetadata);
+
// language description string after the compression technique spec
- std::string languageText((const char*)(data.pData_ + keysize + 3));
- unsigned int languageTextSize = static_cast<unsigned int>(languageText.size());
+ const size_t languageTextMaxSize = data.size_ - keysize - 3;
+ std::string languageText =
+ string_from_unterminated((const char*)(data.pData_ + Safe::add(keysize, 3)), languageTextMaxSize);
+ const unsigned int languageTextSize = static_cast<unsigned int>(languageText.size());
+ enforce(data.size_ >= Safe::add(static_cast<unsigned int>(Safe::add(keysize, 4)), languageTextSize),
+ Exiv2::kerCorruptedMetadata);
+
// translated keyword string after the language description
- std::string translatedKeyText((const char*)(data.pData_ + keysize + 3 + languageTextSize +1));
- unsigned int translatedKeyTextSize = static_cast<unsigned int>(translatedKeyText.size());
+ std::string translatedKeyText =
+ string_from_unterminated((const char*)(data.pData_ + keysize + 3 + languageTextSize + 1),
+ data.size_ - (keysize + 3 + languageTextSize + 1));
+ const unsigned int translatedKeyTextSize = static_cast<unsigned int>(translatedKeyText.size());
- if ( compressionFlag == 0x00 )
- {
- // then it's an uncompressed iTXt chunk
-#ifdef DEBUG
- std::cout << "Exiv2::PngChunk::parseTXTChunk: We found an uncompressed iTXt field\n";
-#endif
+ if ((compressionFlag == 0x00) || (compressionFlag == 0x01 && compressionMethod == 0x00)) {
+ enforce(Safe::add(static_cast<unsigned int>(keysize + 3 + languageTextSize + 1),
+ Safe::add(translatedKeyTextSize, 1u)) <= data.size_,
+ Exiv2::kerCorruptedMetadata);
- // the text comes after the translated keyword, but isn't null terminated
const byte* text = data.pData_ + keysize + 3 + languageTextSize + 1 + translatedKeyTextSize + 1;
- long textsize = data.size_ - (keysize + 3 + languageTextSize + 1 + translatedKeyTextSize + 1);
+ const long textsize = data.size_ - (keysize + 3 + languageTextSize + 1 + translatedKeyTextSize + 1);
- arr.alloc(textsize);
- arr = DataBuf(text, textsize);
- }
- else if ( compressionFlag == 0x01 && compressionMethod == 0x00 )
- {
- // then it's a zlib compressed iTXt chunk
+ if (compressionFlag == 0x00) {
+ // then it's an uncompressed iTXt chunk
#ifdef DEBUG
- std::cout << "Exiv2::PngChunk::parseTXTChunk: We found a zlib compressed iTXt field\n";
+ std::cout << "Exiv2::PngChunk::parseTXTChunk: We found an uncompressed iTXt field\n";
#endif
- // the compressed text comes after the translated keyword, but isn't null terminated
- const byte* compressedText = data.pData_ + keysize + 3 + languageTextSize + 1 + translatedKeyTextSize + 1;
- long compressedTextSize = data.size_ - (keysize + 3 + languageTextSize + 1 + translatedKeyTextSize + 1);
-
- zlibUncompress(compressedText, compressedTextSize, arr);
- }
- else
- {
+ arr.alloc(textsize);
+ arr = DataBuf(text, textsize);
+ } else if (compressionFlag == 0x01 && compressionMethod == 0x00) {
+ // then it's a zlib compressed iTXt chunk
+#ifdef DEBUG
+ std::cout << "Exiv2::PngChunk::parseTXTChunk: We found a zlib compressed iTXt field\n";
+#endif
+ // the compressed text comes after the translated keyword, but isn't null terminated
+ zlibUncompress(text, textsize, arr);
+ }
+ } else {
// then it isn't zlib compressed and we are sunk
#ifdef DEBUG
std::cerr << "Exiv2::PngChunk::parseTXTChunk: Non-standard iTXt compression method.\n";