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libstdc++: Fix overflow handling in std::align

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libstdc++-v3/ChangeLog:

	* include/bits/align.h (align): Fix overflow handling.
	* testsuite/20_util/align/3.cc: New test.
This commit is contained in:
Glen Joseph Fernandes 2020-09-22 17:49:48 +01:00 committed by Jonathan Wakely
parent 7dfffe3241
commit 15139af6fb
2 changed files with 56 additions and 1 deletions
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4
libstdc++-v3/include/bits/align.h
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@ -60,10 +60,12 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
inline void*
align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
{
if (__space < __size)
return nullptr;
const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
const auto __aligned = (__intptr - 1u + __align) & -__align;
const auto __diff = __aligned - __intptr;
if ((__size + __diff) > __space)
if (__diff > (__space - __size))
return nullptr;
else
{

53
libstdc++-v3/testsuite/20_util/align/3.cc Normal file
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@ -0,0 +1,53 @@
// { dg-do run { target c++11 } }
// 2020-09-20 Glen Joseph Fernandes <glenjofe@gmail.com>
// Copyright (C) 2020 Free Software Foundation, Inc.
//
// This file is part of the GNU ISO C++ Library. This library 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 3, or (at your option) any later
// version.
// This library 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 library; see the file COPYING3. If not see
// <http://www.gnu.org/licenses/>.
// C++11 [ptr.align] (20.6.5): std::align
#include <memory>
#include <testsuite_hooks.h>
void test01()
{
void* p1 = reinterpret_cast<void*>(5);
void* p2 = p1;
std::size_t s1 = 3072;
std::size_t s2 = s1;
VERIFY(std::align(1024, static_cast<std::size_t>(-1), p1, s1) == nullptr);
VERIFY(p1 == p2);
VERIFY(s1 == s2);
}
void test02()
{
void* p1 = reinterpret_cast<void*>(1);
void* p2 = p1;
std::size_t s1 = -1;
std::size_t s2 = s1;
VERIFY(std::align(2, static_cast<std::size_t>(-1), p1, s1) == nullptr);
VERIFY(p1 == p2);
VERIFY(s1 == s2);
}
int main()
{
test01();
test02();
}