https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122683
Bug ID: 122683
Summary: In unique_lock.h unlock() routine, _M_owns is
accessed without lock
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: moti.haimovski at intel dot com
Target Milestone: ---
Found by Coverity tests run by me on v11
(/usr/include/c++/11/bits/unique_lock.h)
Also found by RedHat running Coverity tests
(https://people.redhat.com/bhubbard/cov-html-int-2019-10-09/1/152unique_lock.h.html)
Issue is seen also on latest releases.
Detailed test results are below:
void
189 unlock()
190 {
1. Condition !this->_M_owns, taking false branch.
191 if (!_M_owns)
192 __throw_system_error(int(errc::operation_not_permitted));
2. Condition this->_M_device, taking true branch.
193 else if (_M_device)
194 {
195 _M_device->unlock();
CID 10065 (#3 of 3): Data race condition (MISSING_LOCK)3. missing_lock:
Accessing this->_M_owns without holding lock
std::unique_lock<std::mutex>._M_device. Elsewhere,
_ZSt11unique_lockISt5mutexE._M_owns is accessed with
std::unique_lock<std::mutex>._M_device held 1 out of 2 times (1 of these
accesses strongly imply that it is necessary).
196 _M_owns = false;
197 }
198 }
199
