parking_lot.c should check for overflow in Windows _PySemaphore_PlatformWait code path

@vstinner

Bug report

The cast in millis = (DWORD) (timeout / 1000000); may overflow because DWORD is an unsigned 32-bit integer and timeout is a 64-bit integer. We should clamp the result if the cast would overflow.

cpython/Python/parking_lot.c

Lines 93 to 105 in cc7e45c

    
           static int 
        
           _PySemaphore_PlatformWait(_PySemaphore *sema, _PyTime_t timeout) 
        
           { 
        
               int res; 
        
           #if defined(MS_WINDOWS) 
        
               DWORD wait; 
        
               DWORD millis = 0; 
        
               if (timeout < 0) { 
        
                   millis = INFINITE; 
        
               } 
        
               else { 
        
                   millis = (DWORD) (timeout / 1000000); 
        
               }

Noticed by @vstinner in #112733 (review)

Linked PRs

pythongh-112804: Clamping timeout value for _PySemaphore_PlatformWait

gh-112804: Clamping timeout value for _PySemaphore_PlatformWait (gh-1…

pythongh-112804: Clamping timeout value for _PySemaphore_PlatformWait (…

[3.13] gh-112804: Clamping timeout value for _PySemaphore_PlatformWait (

@colesbury

@colesbury, I am closing the issue if we need to reopen it. please let me know.

Thanks for fixing this!

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parking_lot.c should check for overflow in Windows `_PySemaphore_PlatformWait` code path #112804

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	static int
	_PySemaphore_PlatformWait(_PySemaphore *sema, _PyTime_t timeout)
	{
	int res;
	#if defined(MS_WINDOWS)
	DWORD wait;
	DWORD millis = 0;
	if (timeout < 0) {
	millis = INFINITE;
	}
	else {
	millis = (DWORD) (timeout / 1000000);
	}

parking_lot.c should check for overflow in Windows _PySemaphore_PlatformWait code path #112804

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corona10 commented on Oct 8, 2024

colesbury commented on Oct 8, 2024

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parking_lot.c should check for overflow in Windows `_PySemaphore_PlatformWait` code path #112804