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* [gcc r10-9941] libstdc++: Fix null dereferences in std::promise
@ 2021-06-18 12:56 Jonathan Wakely
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From: Jonathan Wakely @ 2021-06-18 12:56 UTC (permalink / raw)
To: gcc-cvs, libstdc++-cvs
https://gcc.gnu.org/g:98efaa7ea4d24355024eae7874309efd60baf97e
commit r10-9941-g98efaa7ea4d24355024eae7874309efd60baf97e
Author: Jonathan Wakely <jwakely@redhat.com>
Date: Tue May 4 16:28:57 2021 +0100
libstdc++: Fix null dereferences in std::promise
This fixes some ubsan errors in std::promise:
future:1153:34: runtime error: member call on null pointer of type 'struct element_type'
future:1153:34: runtime error: member access within null pointer of type 'struct element_type'
The problem is that the check for a null pointer is done inside the
_State::__Setter function, which is only evaluated after evaluating the
_M_future->_M_set_result postfix-expression.
This change adds a new promise::_M_state() helper for accessing
_M_future, and moves the check for no shared state into there, instead
of inside the __setter functions. The __setter functions are made
always_inline, to avoid the situation where the linker selects the old
version of set_value (without the _S_check call) and the new version of
__setter (without the _S_check call) and so there is no check. With the
always_inline attribute the old version of set_value will either inline
the old __setter or call an extern definition of it, and the new
set_value will do the check itself, so both versions do the check.
libstdc++-v3/ChangeLog:
* include/std/future (promise::set_value): Check for existence
of shared state before dereferncing it.
(promise::set_exception, promise::set_value_at_thread_exit)
(promise::set_exception_at_thread_exit): Likewise.
(promise<R&>::set_value, promise<R&>::set_exception)
(promise<R&>::set_value_at_thread_exit)
(promise<R&>::set_exception_at_thread_exit): Likewise.
(promise<void>::set_value, promise<void>::set_exception)
(promise<void>::set_value_at_thread_exit)
(promise<void>::set_exception_at_thread_exit): Likewise.
* testsuite/30_threads/promise/members/at_thread_exit2.cc:
Remove unused variable.
(cherry picked from commit 058d6acefe8bac4a66c8e7fb4951276db188e2d8)
Diff:
---
libstdc++-v3/include/std/future | 64 +++++++++++++++-------
.../30_threads/promise/members/at_thread_exit2.cc | 1 -
2 files changed, 44 insertions(+), 21 deletions(-)
diff --git a/libstdc++-v3/include/std/future b/libstdc++-v3/include/std/future
index ceb1959e3b7..a036dc15682 100644
--- a/libstdc++-v3/include/std/future
+++ b/libstdc++-v3/include/std/future
@@ -533,26 +533,26 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
};
template<typename _Res, typename _Arg>
+ __attribute__((__always_inline__))
static _Setter<_Res, _Arg&&>
- __setter(promise<_Res>* __prom, _Arg&& __arg)
+ __setter(promise<_Res>* __prom, _Arg&& __arg) noexcept
{
- _S_check(__prom->_M_future);
return _Setter<_Res, _Arg&&>{ __prom, std::__addressof(__arg) };
}
template<typename _Res>
+ __attribute__((__always_inline__))
static _Setter<_Res, __exception_ptr_tag>
- __setter(exception_ptr& __ex, promise<_Res>* __prom)
+ __setter(exception_ptr& __ex, promise<_Res>* __prom) noexcept
{
- _S_check(__prom->_M_future);
return _Setter<_Res, __exception_ptr_tag>{ __prom, &__ex };
}
template<typename _Res>
+ __attribute__((__always_inline__))
static _Setter<_Res, void>
- __setter(promise<_Res>* __prom)
+ __setter(promise<_Res>* __prom) noexcept
{
- _S_check(__prom->_M_future);
return _Setter<_Res, void>{ __prom };
}
@@ -1118,36 +1118,44 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Setting the result
void
set_value(const _Res& __r)
- { _M_future->_M_set_result(_State::__setter(this, __r)); }
+ { _M_state()._M_set_result(_State::__setter(this, __r)); }
void
set_value(_Res&& __r)
- { _M_future->_M_set_result(_State::__setter(this, std::move(__r))); }
+ { _M_state()._M_set_result(_State::__setter(this, std::move(__r))); }
void
set_exception(exception_ptr __p)
- { _M_future->_M_set_result(_State::__setter(__p, this)); }
+ { _M_state()._M_set_result(_State::__setter(__p, this)); }
void
set_value_at_thread_exit(const _Res& __r)
{
- _M_future->_M_set_delayed_result(_State::__setter(this, __r),
+ _M_state()._M_set_delayed_result(_State::__setter(this, __r),
_M_future);
}
void
set_value_at_thread_exit(_Res&& __r)
{
- _M_future->_M_set_delayed_result(
+ _M_state()._M_set_delayed_result(
_State::__setter(this, std::move(__r)), _M_future);
}
void
set_exception_at_thread_exit(exception_ptr __p)
{
- _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_state()._M_set_delayed_result(_State::__setter(__p, this),
_M_future);
}
+
+ private:
+ _State&
+ _M_state()
+ {
+ __future_base::_State_base::_S_check(_M_future);
+ return *_M_future;
+ }
};
template<typename _Res>
@@ -1229,25 +1237,33 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Setting the result
void
set_value(_Res& __r)
- { _M_future->_M_set_result(_State::__setter(this, __r)); }
+ { _M_state()._M_set_result(_State::__setter(this, __r)); }
void
set_exception(exception_ptr __p)
- { _M_future->_M_set_result(_State::__setter(__p, this)); }
+ { _M_state()._M_set_result(_State::__setter(__p, this)); }
void
set_value_at_thread_exit(_Res& __r)
{
- _M_future->_M_set_delayed_result(_State::__setter(this, __r),
+ _M_state()._M_set_delayed_result(_State::__setter(this, __r),
_M_future);
}
void
set_exception_at_thread_exit(exception_ptr __p)
{
- _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_state()._M_set_delayed_result(_State::__setter(__p, this),
_M_future);
}
+
+ private:
+ _State&
+ _M_state()
+ {
+ __future_base::_State_base::_S_check(_M_future);
+ return *_M_future;
+ }
};
/// Explicit specialization for promise<void>
@@ -1321,22 +1337,30 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
// Setting the result
void
set_value()
- { _M_future->_M_set_result(_State::__setter(this)); }
+ { _M_state()._M_set_result(_State::__setter(this)); }
void
set_exception(exception_ptr __p)
- { _M_future->_M_set_result(_State::__setter(__p, this)); }
+ { _M_state()._M_set_result(_State::__setter(__p, this)); }
void
set_value_at_thread_exit()
- { _M_future->_M_set_delayed_result(_State::__setter(this), _M_future); }
+ { _M_state()._M_set_delayed_result(_State::__setter(this), _M_future); }
void
set_exception_at_thread_exit(exception_ptr __p)
{
- _M_future->_M_set_delayed_result(_State::__setter(__p, this),
+ _M_state()._M_set_delayed_result(_State::__setter(__p, this),
_M_future);
}
+
+ private:
+ _State&
+ _M_state()
+ {
+ __future_base::_State_base::_S_check(_M_future);
+ return *_M_future;
+ }
};
template<typename _Ptr_type, typename _Fn, typename _Res>
diff --git a/libstdc++-v3/testsuite/30_threads/promise/members/at_thread_exit2.cc b/libstdc++-v3/testsuite/30_threads/promise/members/at_thread_exit2.cc
index 59eeae823ec..7db52a6336e 100644
--- a/libstdc++-v3/testsuite/30_threads/promise/members/at_thread_exit2.cc
+++ b/libstdc++-v3/testsuite/30_threads/promise/members/at_thread_exit2.cc
@@ -119,7 +119,6 @@ void test02()
void test03()
{
std::promise<void> p1;
- int i = 0;
p1.set_value();
try {
p1.set_value_at_thread_exit();
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