From 7c6f59619616a01e242401cf4c8e06428539a035 Mon Sep 17 00:00:00 2001

From: Luis Diaz Mas <piponazo@gmail.com>

Date: Sat, 16 Dec 2017 16:05:08 +0100

Subject: Fix arithmetic operation overflow

diff --git a/src/jp2image.cpp b/src/jp2image.cpp

index 09d023e2..a308bfd9 100644

--- a/src/jp2image.cpp

+++ b/src/jp2image.cpp

@@ -41,6 +41,7 @@ EXIV2_RCSID("@(#) $Id$")

 #include "error.hpp"

 #include "futils.hpp"

 #include "types.hpp"

+#include "safe_op.hpp"

 // + standard includes

 #include <string>

@@ -269,15 +270,16 @@ namespace Exiv2

                             std::cout << "Exiv2::Jp2Image::readMetadata: "

                                      << "Color data found" << std::endl;

 #endif

+

                             const long pad = 3 ; // 3 padding bytes 2 0 0

-                            DataBuf data(subBox.length+8);

+                            DataBuf data(Safe::add(subBox.length, static_cast<uint32_t>(8)));

                             io_->read(data.pData_,data.size_);

                             const long    iccLength = getULong(data.pData_+pad, bigEndian);

                             // subtracting pad from data.size_ is safe:

                             // size_ is at least 8 and pad = 3

                             if (iccLength > data.size_ - pad) {

                                 throw Error(58);

-			    }

+                            }

                             DataBuf icc(iccLength);

                             ::memcpy(icc.pData_,data.pData_+pad,icc.size_);

 #ifdef DEBUG

diff --git a/src/safe_op.hpp b/src/safe_op.hpp

new file mode 100644

index 00000000..55d690e3

--- /dev/null

+++ b/src/safe_op.hpp

@@ -0,0 +1,308 @@

+// ********************************************************* -*- C++ -*-

+/*

+ * Copyright (C) 2004-2017 Exiv2 maintainers

+ *

+ * 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    safe_op.hpp

+  @brief   Overflow checks for integers

+  @author  Dan Čermák (D4N)

+           dan.cermak@cgc-instruments.com

+  @date    14-Dec-17, D4N: created

+ */

+

+#ifndef SAFE_OP_HPP_

+#define SAFE_OP_HPP_

+

+#include <limits>

+#include <stdexcept>

+

+#ifdef _MSC_VER

+#include <Intsafe.h>

+#endif

+

+/*!

+ * @brief Arithmetic operations with overflow checks

+ */

+namespace Safe

+{

+    /*!

+     * @brief Helper structs for providing integer overflow checks.

+     *

+     * This namespace contains the internal helper structs fallback_add_overflow

+     * and builtin_add_overflow. Both have a public static member function add

+     * with the following interface:

+     *

+     * bool add(T summand_1, T summand_2, T& result)

+     *

+     * where T is the type over which the struct is templated.

+     *

+     * The function performs a check whether the addition summand_1 + summand_2

+     * can be performed without an overflow. If the operation would overflow,

+     * true is returned and the addition is not performed if it would result in

+     * undefined behavior. If no overflow occurs, the sum is saved in result and

+     * false is returned.

+     *

+     * fallback_add_overflow implements a portable but slower overflow check.

+     * builtin_add_overflow uses compiler builtins (when available) and should

+     * be considerably faster. As builtins are not available for all types,

+     * builtin_add_overflow falls back to fallback_add_overflow when no builtin

+     * is available.

+     */

+    namespace Internal

+    {

+        /*!

+         * @brief Helper struct to determine whether a type is signed or unsigned

+

+         * This struct is a backport of std::is_signed from C++11. It has a public

+         * enum with the property VALUE which is true when the type is signed or

+         * false if it is unsigned.

+         */

+        template <typename T>

+        struct is_signed

+        {

+            enum

+            {

+                VALUE = T(-1) < T(0)

+            };

+        };

+

+        /*!

+         * @brief Helper struct for SFINAE, from C++11

+

+         * This struct has a public typedef called type typedef'd to T if B is

+         * true. Otherwise there is no typedef.

+         */

+        template <bool B, class T = void>

+        struct enable_if

+        {

+        };

+

+        /*!

+         * @brief Specialization of enable_if for the case B == true

+         */

+        template <class T>

+        struct enable_if<true, T>

+        {

+            typedef T type;

+        };

+

+        /*!

+         * @brief Fallback overflow checker, specialized via SFINAE

+         *

+         * This struct implements a 'fallback' addition with an overflow check,

+         * i.e. it does not rely on compiler intrinsics.  It is specialized via

+         * SFINAE for signed and unsigned integer types and provides a public

+         * static member function add.

+         */

+        template <typename T, typename = void>

+        struct fallback_add_overflow;

+

+        /*!

+         * @brief Overload of fallback_add_overflow for signed integers

+         */

+        template <typename T>

+        struct fallback_add_overflow<T, typename enable_if<is_signed<T>::VALUE>::type>

+        {

+            /*!

+             * @brief Adds the two summands only if no overflow occurs

+             *

+             * This function performs a check if summand_1 + summand_2 would

+             * overflow and returns true in that case. If no overflow occurs,

+             * the sum is saved in result and false is returned.

+             *

+             * @return true on overflow, false on no overflow

+             *

+             * The check for an overflow is performed before the addition to

+             * ensure that no undefined behavior occurs. The value in result is

+             * only valid when the function returns false.

+             *

+             * Further information:

+             * https://wiki.sei.cmu.edu/confluence/display/c/INT32-C.+Ensure+that+operations+on+signed+integers+do+not+result+in+overflow

+             */

+            static bool add(T summand_1, T summand_2, T& result)

+            {

+                if (((summand_2 >= 0) && (summand_1 > std::numeric_limits<T>::max() - summand_2)) ||

+                    ((summand_2 < 0) && (summand_1 < std::numeric_limits<T>::min() - summand_2))) {

+                    return true;

+                } else {

+                    result = summand_1 + summand_2;

+                    return false;

+                }

+            }

+        };

+

+        /*!

+         * @brief Overload of fallback_add_overflow for unsigned integers

+         */

+        template <typename T>

+        struct fallback_add_overflow<T, typename enable_if<!is_signed<T>::VALUE>::type>

+        {

+            /*!

+             * @brief Adds the two summands only if no overflow occurs

+             *

+             * This function performs a check if summand_1 + summand_2 would

+             * overflow and returns true in that case. If no overflow occurs,

+             * the sum is saved in result and false is returned.

+             *

+             * @return true on overflow, false on no overflow

+             *

+             * Further information:

+             * https://wiki.sei.cmu.edu/confluence/display/c/INT30-C.+Ensure+that+unsigned+integer+operations+do+not+wrap

+             */

+            static bool add(T summand_1, T summand_2, T& result)

+            {

+                if (summand_1 > std::numeric_limits<T>::max() - summand_2) {

+                    return true;

+                } else {

+                    result = summand_1 + summand_2;

+                    return false;

+                }

+            }

+        };

+

+        /*!

+         * @brief Overflow checker using compiler intrinsics

+         *

+         * This struct provides an add function with the same interface &

+         * behavior as fallback_add_overload::add but it relies on compiler

+         * intrinsics instead. This version should be considerably faster than

+         * the fallback version as it can fully utilize available CPU

+         * instructions & the compiler's diagnostic.

+         *

+         * However, as some compilers don't provide intrinsics for certain

+         * types, the default implementation of add is the version from falback.

+         *

+         * The struct is explicitly specialized for each type via #ifdefs for

+         * each compiler.

+         */

+        template <typename T>

+        struct builtin_add_overflow

+        {

+            /*!

+             * @brief Add summand_1 and summand_2 and check for overflows.

+             *

+             * This is the default add() function that uses

+             * fallback_add_overflow<T>::add(). All specializations must have

+             * exactly the same interface and behave the same way.

+             */

+            static inline bool add(T summand_1, T summand_2, T& result)

+            {

+                return fallback_add_overflow<T>::add(summand_1, summand_2, result);

+            }

+        };

+

+#if defined(__GNUC__) || defined(__clang__)

+

+/*!

+ * This macro pastes a specialization of builtin_add_overflow using gcc's &

+ * clang's __builtin_(s/u)add(l)(l)_overlow()

+ *

+ * The add function is implemented by forwarding the parameters to the intrinsic

+ * and returning its value.

+ *

+ * The intrinsics are documented here:

+ * https://gcc.gnu.org/onlinedocs/gcc/Integer-Overflow-Builtins.html#Integer-Overflow-Builtins

+ */

+#define SPECIALIZE_builtin_add_overflow(type, builtin_name)                  \

+    template <>                                                              \

+    struct builtin_add_overflow<type>                                        \

+    {                                                                        \

+        static inline bool add(type summand_1, type summand_2, type& result) \

+        {                                                                    \

+            return builtin_name(summand_1, summand_2, &result);              \

+        }                                                                    \

+    }

+

+        SPECIALIZE_builtin_add_overflow(int, __builtin_sadd_overflow);

+        SPECIALIZE_builtin_add_overflow(long, __builtin_saddl_overflow);

+        SPECIALIZE_builtin_add_overflow(long long, __builtin_saddll_overflow);

+

+        SPECIALIZE_builtin_add_overflow(unsigned int, __builtin_uadd_overflow);

+        SPECIALIZE_builtin_add_overflow(unsigned long, __builtin_uaddl_overflow);

+        SPECIALIZE_builtin_add_overflow(unsigned long long, __builtin_uaddll_overflow);

+

+#undef SPECIALIZE_builtin_add_overflow

+

+#elif defined(_MSC_VER)

+

+/*!

+ * This macro pastes a specialization of builtin_add_overflow using MSVC's

+ * U(Int/Long/LongLong)Add.

+ *

+ * The add function is implemented by forwarding the parameters to the

+ * intrinsic. As MSVC's intrinsics return S_OK on success, this specialization

+ * returns whether the intrinsics return value does not equal S_OK. This ensures

+ * a uniform interface of the add function (false is returned when no overflow

+ * occurs, true on overflow).

+ *

+ * The intrinsics are documented here:

+ * https://msdn.microsoft.com/en-us/library/windows/desktop/ff516460(v=vs.85).aspx

+ */

+#define SPECIALIZE_builtin_add_overflow_WIN(type, builtin_name)              \

+    template <>                                                              \

+    struct builtin_add_overflow<type>                                        \

+    {                                                                        \

+        static inline bool add(type summand_1, type summand_2, type& result) \

+        {                                                                    \

+            return builtin_name(summand_1, summand_2, &result) != S_OK;      \

+        }                                                                    \

+    }

+

+        SPECIALIZE_builtin_add_overflow_WIN(unsigned int, UIntAdd);

+        SPECIALIZE_builtin_add_overflow_WIN(unsigned long, ULongAdd);

+        SPECIALIZE_builtin_add_overflow_WIN(unsigned long long, ULongLongAdd);

+

+#undef SPECIALIZE_builtin_add_overflow_WIN

+

+#endif

+

+    }  // namespace Internal

+

+    /*!

+     * @brief Safe addition, throws an exception on overflow.

+     *

+     * This function returns the result of summand_1 and summand_2 only when the

+     * operation would not overflow, otherwise an exception of type

+     * std::overflow_error is thrown.

+     *

+     * @param[in] summand_1, summand_2  summands to be summed up

+     * @return  the sum of summand_1 and summand_2

+     * @throws  std::overflow_error if the addition would overflow

+     *

+     * This function utilizes compiler builtins when available and should have a

+     * very small performance hit then. When builtins are unavailable, a more

+     * extensive check is required.

+     *

+     * Builtins are available for the following configurations:

+     * - GCC/Clang for signed and unsigned int, long and long long (not char & short)

+     * - MSVC for unsigned int, long and long long

+     */

+    template <typename T>

+    T add(T summand_1, T summand_2)

+    {

+        T res = 0;

+        if (Internal::builtin_add_overflow<T>::add(summand_1, summand_2, res)) {

+            throw std::overflow_error("Overflow in addition");

+        }

+        return res;

+    }

+

+}  // namespace Safe

+

+#endif  // SAFE_OP_HPP_