From: Jonathan Wakely <jwakely@redhat.com>
To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org
Subject: [committed] libstdc++: Check for overflow in regex back-reference [PR106607]
Date: Mon, 22 Aug 2022 22:53:09 +0100 [thread overview]
Message-ID: <20220822215309.92952-1-jwakely@redhat.com> (raw)
Tested powerpc64le-linux, pushed to trunk. Worth backporting.
-- >8 --
Currently we fail to notice integer overflow when parsing a
back-reference expression, or when converting the parsed result from
long to int. This changes the result to be int, so no conversion is
needed, and uses the overflow-checking built-ins to detect an
out-of-range back-reference.
libstdc++-v3/ChangeLog:
PR libstdc++/106607
* include/bits/regex_compiler.tcc (_Compiler::_M_cur_int_value):
Use built-ins to check for integer overflow in back-reference
number.
* testsuite/28_regex/basic_regex/106607.cc: New test.
---
libstdc++-v3/include/bits/regex_compiler.tcc | 10 +++++---
.../testsuite/28_regex/basic_regex/106607.cc | 25 +++++++++++++++++++
2 files changed, 31 insertions(+), 4 deletions(-)
create mode 100644 libstdc++-v3/testsuite/28_regex/basic_regex/106607.cc
diff --git a/libstdc++-v3/include/bits/regex_compiler.tcc b/libstdc++-v3/include/bits/regex_compiler.tcc
index c12f7502538..9f3ca63af51 100644
--- a/libstdc++-v3/include/bits/regex_compiler.tcc
+++ b/libstdc++-v3/include/bits/regex_compiler.tcc
@@ -583,10 +583,12 @@ namespace __detail
_Compiler<_TraitsT>::
_M_cur_int_value(int __radix)
{
- long __v = 0;
- for (typename _StringT::size_type __i = 0;
- __i < _M_value.length(); ++__i)
- __v =__v * __radix + _M_traits.value(_M_value[__i], __radix);
+ int __v = 0;
+ for (_CharT __c : _M_value)
+ if (__builtin_mul_overflow(__v, __radix, &__v)
+ || __builtin_add_overflow(__v, _M_traits.value(__c, __radix), &__v))
+ std::__throw_regex_error(regex_constants::error_backref,
+ "invalid back reference");
return __v;
}
diff --git a/libstdc++-v3/testsuite/28_regex/basic_regex/106607.cc b/libstdc++-v3/testsuite/28_regex/basic_regex/106607.cc
new file mode 100644
index 00000000000..f8e7fb2364d
--- /dev/null
+++ b/libstdc++-v3/testsuite/28_regex/basic_regex/106607.cc
@@ -0,0 +1,25 @@
+// { dg-do run { target c++11 } }
+
+#include <regex>
+#include <string>
+#include <climits>
+#include <testsuite_hooks.h>
+
+// PR libstdc++/106607 - Regex integer overflow on large backreference value
+
+int main()
+{
+ std::regex r("(.)\\1"); // OK
+
+ try
+ {
+ long long n = (unsigned)-1 + 2LL; // 4294967297 for 32-bit int
+ VERIFY( (int)n == 1 ); // 4294967297 % 2^32 == 1
+ std::regex r("(.)\\" + std::to_string(n)); // Invalid back reference.
+ VERIFY(false);
+ }
+ catch (const std::regex_error& e)
+ {
+ VERIFY( e.code() == std::regex_constants::error_backref );
+ }
+}
--
2.37.2
reply other threads:[~2022-08-22 21:53 UTC|newest]
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