gh-112804: Clamping timeout value for _PySemaphore_PlatformWait (gh-124914)

* gh-112804: Clamping timeout value for _PySemaphore_PlatformWait

* Address code review

* nit

diff --git a/Python/parking_lot.c b/Python/parking_lot.c
index 841b1d71ea16cb1183ae154a5110c59cd99a534f..a7e9760e35d87a806f7b4e3b8865cefd56e2e3c2 100644 (file)
--- a/Python/parking_lot.c
+++ b/Python/parking_lot.c
@@ -102,7 +102,14 @@ _PySemaphore_PlatformWait(_PySemaphore *sema, PyTime_t timeout)
         millis = INFINITE;
     }
     else {
-        millis = (DWORD) (timeout / 1000000);
+        PyTime_t div = _PyTime_AsMilliseconds(timeout, _PyTime_ROUND_TIMEOUT);
+        // Prevent overflow with clamping the result
+        if ((PyTime_t)PY_DWORD_MAX < div) {
+            millis = PY_DWORD_MAX;
+        }
+        else {
+            millis = (DWORD) div;
+        }
     }
     wait = WaitForSingleObjectEx(sema->platform_sem, millis, FALSE);
     if (wait == WAIT_OBJECT_0) {