From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: by sourceware.org (Postfix, from userid 2122) id 402C93858D39; Sat, 11 Dec 2021 04:58:24 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 402C93858D39 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="utf-8" From: Jason Merrill To: gcc-cvs@gcc.gnu.org, libstdc++-cvs@gcc.gnu.org Subject: [gcc r12-5906] libstdc++: check length in string append [PR103534] X-Act-Checkin: gcc X-Git-Author: Jason Merrill X-Git-Refname: refs/heads/master X-Git-Oldrev: 0bceef1671adee52e9cc409d82e5f5590fed8d45 X-Git-Newrev: 2e8067041d1d69da02bd7578f58abc11eb35a04b Message-Id: <20211211045824.402C93858D39@sourceware.org> Date: Sat, 11 Dec 2021 04:58:24 +0000 (GMT) X-BeenThere: libstdc++-cvs@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libstdc++-cvs mailing list List-Unsubscribe: , List-Archive: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 11 Dec 2021 04:58:24 -0000 https://gcc.gnu.org/g:2e8067041d1d69da02bd7578f58abc11eb35a04b commit r12-5906-g2e8067041d1d69da02bd7578f58abc11eb35a04b Author: Jason Merrill Date: Fri Dec 10 11:21:50 2021 -0500 libstdc++: check length in string append [PR103534] In the testcase for 103534 we get a warning about append leading to memcpy of a very large number of bytes overflowing the buffer. This turns out to be because we weren't calling _M_check_length for string append. Rather than do that directly, let's go through the public pointer append that calls it. PR c++/103534 libstdc++-v3/ChangeLog: * include/bits/basic_string.h (append (basic_string)): Call pointer append instead of _M_append directly. gcc/testsuite/ChangeLog: * g++.dg/warn/Wstringop-overflow-8.C: New test. Diff: --- libstdc++-v3/include/bits/basic_string.h | 8 ++++---- gcc/testsuite/g++.dg/warn/Wstringop-overflow-8.C | 10 ++++++++++ 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/libstdc++-v3/include/bits/basic_string.h b/libstdc++-v3/include/bits/basic_string.h index 4007a8d2d7c..3da2f8088ac 100644 --- a/libstdc++-v3/include/bits/basic_string.h +++ b/libstdc++-v3/include/bits/basic_string.h @@ -1382,7 +1382,7 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 _GLIBCXX20_CONSTEXPR basic_string& append(const basic_string& __str) - { return _M_append(__str._M_data(), __str.size()); } + { return this->append(__str._M_data(), __str.size()); } /** * @brief Append a substring. @@ -1400,9 +1400,9 @@ _GLIBCXX_BEGIN_NAMESPACE_CXX11 _GLIBCXX20_CONSTEXPR basic_string& append(const basic_string& __str, size_type __pos, size_type __n = npos) - { return _M_append(__str._M_data() - + __str._M_check(__pos, "basic_string::append"), - __str._M_limit(__pos, __n)); } + { return this->append(__str._M_data() + + __str._M_check(__pos, "basic_string::append"), + __str._M_limit(__pos, __n)); } /** * @brief Append a C substring. diff --git a/gcc/testsuite/g++.dg/warn/Wstringop-overflow-8.C b/gcc/testsuite/g++.dg/warn/Wstringop-overflow-8.C new file mode 100644 index 00000000000..d0ef5e73f93 --- /dev/null +++ b/gcc/testsuite/g++.dg/warn/Wstringop-overflow-8.C @@ -0,0 +1,10 @@ +// PR c++/103534 +// { dg-additional-options "-O -Wall" } + +#include + +std::string foo(std::string x) +{ + // This used to get a bogus -Wstringop-overflow warning. + return std::string("1234567890123456") + x; +}