This is the general case of Bug 113327. That one is specific to this_thread::sleep_for but we have the same issue in other places where we convert a relative timeout to chrono::seconds. If the original type has a coarser duration than seconds, the value might overflow chrono::seconds::rep. This affects timed mutexes, condition variables, futures ...
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>: https://gcc.gnu.org/g:5dba17a3e709859968f939354e6e5e8d796012d3 commit r16-4425-g5dba17a3e709859968f939354e6e5e8d796012d3 Author: Jonathan Wakely <jwakely@redhat.com> Date: Thu Oct 9 11:09:34 2025 +0100 libstdc++: Avoid overflow in timeout conversions [PR113327] When converting from a coarse duration with a very large value, the existing code scales that up to chrono::seconds which overflows the chrono::seconds::rep type. For example, sleep_for(chrono::hours::max()) tries to calculate LLONG_MAX * 3600, which overflows to -3600 and so the sleep returns immediately. The solution in this commit is inspired by this_thread::sleep_for in libc++ which compares the duration argument to chrono::duration<long double>(nanoseconds::max()) and limits the duration to nanoseconds::max(). Because we split the duration into seconds and nanoseconds, we can use seconds::max() as our upper limit. We might need to limit further if seconds::max() doesn't fit in the type used for sleeping, which is one of std::time_t, unsigned int, or chrono::milliseconds. To fix this everywhere that uses timeouts, new functions are introduced for converting from a chrono::duration or chrono::time_point to a timespec (or __gthread_time_t which is just a timespec on Linux). These functions provide one central place where we can avoid overflow and also handle negative timeouts (as these produce errors when passed to OS functions that do not accept absolute times before the epoch). All negative durations are converted to zero, and negative time_points are converted to the epoch. The new __to_timeout_gthread_time_t function in <bits/std_mutex.h> requires adding <bits/chrono.h> to that header, but that only affects <syncstream>. All other consumers of <bits/std_mutex.h> were already including <bits/chrono.h> for timeouts (e.g. <shared_mutex> and <condition_variable>). libstdc++-v3/ChangeLog: PR libstdc++/113327 PR libstdc++/116586 PR libstdc++/119258 PR libstdc++/58931 * include/bits/chrono.h (__to_timeout_timespec): New overloaded function templates for converting chrono types to timespec. * include/bits/std_mutex.h (__to_timeout_gthread_time_t): New function template for converting time_point to __gthread_time_t. * include/bits/this_thread_sleep.h (sleep_for): Use __to_timeout_timespec. (__sleep_for): Remove namespace-scope declaration. * include/std/condition_variable: Likewise. * include/std/mutex: Likewise. * include/std/shared_mutex: Likewise. * src/c++11/thread.cc (limit): New helper function. (__sleep_for): Use limit to prevent overflow when converting chrono::seconds to time_t, unsigned, or chrono::milliseconds. * src/c++20/atomic.cc: Use __to_timeout_timespec and __to_timeout_gthread_time_t for timeouts. * testsuite/30_threads/this_thread/113327.cc: New test. Reviewed-by: Mike Crowe <mac@mcrowe.com> Reviewed-by: Tomasz KamiÅski <tkaminsk@redhat.com>
Fixed for GCC 16