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352 lines
14 KiB
352 lines
14 KiB
From 7c6f59619616a01e242401cf4c8e06428539a035 Mon Sep 17 00:00:00 2001
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From: Luis Diaz Mas <piponazo@gmail.com>
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Date: Sat, 16 Dec 2017 16:05:08 +0100
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Subject: Fix arithmetic operation overflow
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diff --git a/src/jp2image.cpp b/src/jp2image.cpp
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index 09d023e2..a308bfd9 100644
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--- a/src/jp2image.cpp
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+++ b/src/jp2image.cpp
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@@ -41,6 +41,7 @@ EXIV2_RCSID("@(#) $Id$")
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#include "error.hpp"
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#include "futils.hpp"
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#include "types.hpp"
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+#include "safe_op.hpp"
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// + standard includes
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#include <string>
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@@ -269,15 +270,16 @@ namespace Exiv2
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std::cout << "Exiv2::Jp2Image::readMetadata: "
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<< "Color data found" << std::endl;
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#endif
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+
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const long pad = 3 ; // 3 padding bytes 2 0 0
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- DataBuf data(subBox.length+8);
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+ DataBuf data(Safe::add(subBox.length, static_cast<uint32_t>(8)));
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io_->read(data.pData_,data.size_);
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const long iccLength = getULong(data.pData_+pad, bigEndian);
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// subtracting pad from data.size_ is safe:
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// size_ is at least 8 and pad = 3
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if (iccLength > data.size_ - pad) {
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throw Error(58);
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- }
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+ }
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DataBuf icc(iccLength);
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::memcpy(icc.pData_,data.pData_+pad,icc.size_);
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#ifdef DEBUG
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diff --git a/src/safe_op.hpp b/src/safe_op.hpp
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new file mode 100644
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index 00000000..55d690e3
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--- /dev/null
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+++ b/src/safe_op.hpp
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@@ -0,0 +1,308 @@
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+// ********************************************************* -*- C++ -*-
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+/*
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+ * Copyright (C) 2004-2017 Exiv2 maintainers
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+ *
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+ * This program is part of the Exiv2 distribution.
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+ *
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+ * This program is free software; you can redistribute it and/or
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+ * modify it under the terms of the GNU General Public License
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+ * as published by the Free Software Foundation; either version 2
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+ * of the License, or (at your option) any later version.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ * You should have received a copy of the GNU General Public License
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+ * along with this program; if not, write to the Free Software
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+ * Foundation, Inc., 51 Franklin Street, 5th Floor, Boston, MA 02110-1301 USA.
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+ */
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+/*!
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+ @file safe_op.hpp
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+ @brief Overflow checks for integers
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+ @author Dan Čermák (D4N)
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+ <a href="mailto:dan.cermak@cgc-instruments.com">dan.cermak@cgc-instruments.com</a>
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+ @date 14-Dec-17, D4N: created
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+ */
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+
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+#ifndef SAFE_OP_HPP_
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+#define SAFE_OP_HPP_
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+
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+#include <limits>
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+#include <stdexcept>
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+
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+#ifdef _MSC_VER
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+#include <Intsafe.h>
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+#endif
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+
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+/*!
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+ * @brief Arithmetic operations with overflow checks
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+ */
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+namespace Safe
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+{
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+ /*!
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+ * @brief Helper structs for providing integer overflow checks.
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+ *
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+ * This namespace contains the internal helper structs fallback_add_overflow
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+ * and builtin_add_overflow. Both have a public static member function add
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+ * with the following interface:
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+ *
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+ * bool add(T summand_1, T summand_2, T& result)
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+ *
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+ * where T is the type over which the struct is templated.
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+ *
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+ * The function performs a check whether the addition summand_1 + summand_2
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+ * can be performed without an overflow. If the operation would overflow,
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+ * true is returned and the addition is not performed if it would result in
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+ * undefined behavior. If no overflow occurs, the sum is saved in result and
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+ * false is returned.
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+ *
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+ * fallback_add_overflow implements a portable but slower overflow check.
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+ * builtin_add_overflow uses compiler builtins (when available) and should
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+ * be considerably faster. As builtins are not available for all types,
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+ * builtin_add_overflow falls back to fallback_add_overflow when no builtin
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+ * is available.
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+ */
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+ namespace Internal
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+ {
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+ /*!
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+ * @brief Helper struct to determine whether a type is signed or unsigned
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+
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+ * This struct is a backport of std::is_signed from C++11. It has a public
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+ * enum with the property VALUE which is true when the type is signed or
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+ * false if it is unsigned.
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+ */
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+ template <typename T>
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+ struct is_signed
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+ {
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+ enum
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+ {
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+ VALUE = T(-1) < T(0)
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+ };
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+ };
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+
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+ /*!
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+ * @brief Helper struct for SFINAE, from C++11
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+
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+ * This struct has a public typedef called type typedef'd to T if B is
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+ * true. Otherwise there is no typedef.
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+ */
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+ template <bool B, class T = void>
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+ struct enable_if
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+ {
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+ };
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+
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+ /*!
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+ * @brief Specialization of enable_if for the case B == true
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+ */
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+ template <class T>
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+ struct enable_if<true, T>
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+ {
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+ typedef T type;
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+ };
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+
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+ /*!
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+ * @brief Fallback overflow checker, specialized via SFINAE
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+ *
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+ * This struct implements a 'fallback' addition with an overflow check,
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+ * i.e. it does not rely on compiler intrinsics. It is specialized via
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+ * SFINAE for signed and unsigned integer types and provides a public
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+ * static member function add.
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+ */
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+ template <typename T, typename = void>
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+ struct fallback_add_overflow;
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+
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+ /*!
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+ * @brief Overload of fallback_add_overflow for signed integers
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+ */
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+ template <typename T>
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+ struct fallback_add_overflow<T, typename enable_if<is_signed<T>::VALUE>::type>
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+ {
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+ /*!
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+ * @brief Adds the two summands only if no overflow occurs
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+ *
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+ * This function performs a check if summand_1 + summand_2 would
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+ * overflow and returns true in that case. If no overflow occurs,
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+ * the sum is saved in result and false is returned.
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+ *
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+ * @return true on overflow, false on no overflow
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+ *
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+ * The check for an overflow is performed before the addition to
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+ * ensure that no undefined behavior occurs. The value in result is
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+ * only valid when the function returns false.
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+ *
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+ * Further information:
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+ * https://wiki.sei.cmu.edu/confluence/display/c/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow
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+ */
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+ static bool add(T summand_1, T summand_2, T& result)
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+ {
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+ if (((summand_2 >= 0) && (summand_1 > std::numeric_limits<T>::max() - summand_2)) ||
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+ ((summand_2 < 0) && (summand_1 < std::numeric_limits<T>::min() - summand_2))) {
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+ return true;
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+ } else {
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+ result = summand_1 + summand_2;
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+ return false;
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+ }
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+ }
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+ };
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+
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+ /*!
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+ * @brief Overload of fallback_add_overflow for unsigned integers
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+ */
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+ template <typename T>
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+ struct fallback_add_overflow<T, typename enable_if<!is_signed<T>::VALUE>::type>
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+ {
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+ /*!
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+ * @brief Adds the two summands only if no overflow occurs
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+ *
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+ * This function performs a check if summand_1 + summand_2 would
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+ * overflow and returns true in that case. If no overflow occurs,
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+ * the sum is saved in result and false is returned.
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+ *
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+ * @return true on overflow, false on no overflow
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+ *
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+ * Further information:
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+ * https://wiki.sei.cmu.edu/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap
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+ */
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+ static bool add(T summand_1, T summand_2, T& result)
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+ {
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+ if (summand_1 > std::numeric_limits<T>::max() - summand_2) {
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+ return true;
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+ } else {
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+ result = summand_1 + summand_2;
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+ return false;
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+ }
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+ }
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+ };
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+
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+ /*!
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+ * @brief Overflow checker using compiler intrinsics
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+ *
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+ * This struct provides an add function with the same interface &
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+ * behavior as fallback_add_overload::add but it relies on compiler
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+ * intrinsics instead. This version should be considerably faster than
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+ * the fallback version as it can fully utilize available CPU
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+ * instructions & the compiler's diagnostic.
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+ *
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+ * However, as some compilers don't provide intrinsics for certain
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+ * types, the default implementation of add is the version from falback.
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+ *
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+ * The struct is explicitly specialized for each type via #ifdefs for
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+ * each compiler.
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+ */
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+ template <typename T>
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+ struct builtin_add_overflow
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+ {
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+ /*!
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+ * @brief Add summand_1 and summand_2 and check for overflows.
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+ *
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+ * This is the default add() function that uses
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+ * fallback_add_overflow<T>::add(). All specializations must have
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+ * exactly the same interface and behave the same way.
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+ */
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+ static inline bool add(T summand_1, T summand_2, T& result)
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+ {
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+ return fallback_add_overflow<T>::add(summand_1, summand_2, result);
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+ }
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+ };
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+
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+#if defined(__GNUC__) || defined(__clang__)
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+
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+/*!
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+ * This macro pastes a specialization of builtin_add_overflow using gcc's &
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+ * clang's __builtin_(s/u)add(l)(l)_overlow()
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+ *
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+ * The add function is implemented by forwarding the parameters to the intrinsic
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+ * and returning its value.
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+ *
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+ * The intrinsics are documented here:
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+ * https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html#Integer-Overflow-Builtins
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+ */
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+#define SPECIALIZE_builtin_add_overflow(type, builtin_name) \
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+ template <> \
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+ struct builtin_add_overflow<type> \
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+ { \
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+ static inline bool add(type summand_1, type summand_2, type& result) \
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+ { \
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+ return builtin_name(summand_1, summand_2, &result); \
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+ } \
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+ }
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+
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+ SPECIALIZE_builtin_add_overflow(int, __builtin_sadd_overflow);
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+ SPECIALIZE_builtin_add_overflow(long, __builtin_saddl_overflow);
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+ SPECIALIZE_builtin_add_overflow(long long, __builtin_saddll_overflow);
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+
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+ SPECIALIZE_builtin_add_overflow(unsigned int, __builtin_uadd_overflow);
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+ SPECIALIZE_builtin_add_overflow(unsigned long, __builtin_uaddl_overflow);
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+ SPECIALIZE_builtin_add_overflow(unsigned long long, __builtin_uaddll_overflow);
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+
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+#undef SPECIALIZE_builtin_add_overflow
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+
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+#elif defined(_MSC_VER)
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+
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+/*!
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+ * This macro pastes a specialization of builtin_add_overflow using MSVC's
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+ * U(Int/Long/LongLong)Add.
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+ *
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+ * The add function is implemented by forwarding the parameters to the
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+ * intrinsic. As MSVC's intrinsics return S_OK on success, this specialization
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+ * returns whether the intrinsics return value does not equal S_OK. This ensures
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+ * a uniform interface of the add function (false is returned when no overflow
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+ * occurs, true on overflow).
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+ *
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+ * The intrinsics are documented here:
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+ * https://msdn.microsoft.com/en-us/library/windows/desktop/ff516460(v=vs.85).aspx
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+ */
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+#define SPECIALIZE_builtin_add_overflow_WIN(type, builtin_name) \
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+ template <> \
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+ struct builtin_add_overflow<type> \
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+ { \
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+ static inline bool add(type summand_1, type summand_2, type& result) \
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+ { \
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+ return builtin_name(summand_1, summand_2, &result) != S_OK; \
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+ } \
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+ }
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+
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+ SPECIALIZE_builtin_add_overflow_WIN(unsigned int, UIntAdd);
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+ SPECIALIZE_builtin_add_overflow_WIN(unsigned long, ULongAdd);
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+ SPECIALIZE_builtin_add_overflow_WIN(unsigned long long, ULongLongAdd);
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+
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+#undef SPECIALIZE_builtin_add_overflow_WIN
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+
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+#endif
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+
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+ } // namespace Internal
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+
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+ /*!
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+ * @brief Safe addition, throws an exception on overflow.
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+ *
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+ * This function returns the result of summand_1 and summand_2 only when the
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+ * operation would not overflow, otherwise an exception of type
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+ * std::overflow_error is thrown.
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+ *
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+ * @param[in] summand_1, summand_2 summands to be summed up
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+ * @return the sum of summand_1 and summand_2
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+ * @throws std::overflow_error if the addition would overflow
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+ *
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+ * This function utilizes compiler builtins when available and should have a
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+ * very small performance hit then. When builtins are unavailable, a more
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+ * extensive check is required.
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+ *
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+ * Builtins are available for the following configurations:
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+ * - GCC/Clang for signed and unsigned int, long and long long (not char & short)
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+ * - MSVC for unsigned int, long and long long
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+ */
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+ template <typename T>
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+ T add(T summand_1, T summand_2)
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+ {
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+ T res = 0;
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+ if (Internal::builtin_add_overflow<T>::add(summand_1, summand_2, res)) {
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+ throw std::overflow_error("Overflow in addition");
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+ }
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+ return res;
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+ }
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+
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+} // namespace Safe
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+
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+#endif // SAFE_OP_HPP_
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