554419 - Possible address space leak in VMPI_decommitMemory()

Status: VERIFIED INVALID

(Tamarin Graveyard :: Garbage Collection (mmGC), defect)

Description

[William Maddox]

MSVC++ static code analysis (/analyze) reports the following:

>z:\wmaddox\tr-patch\vmpi\mmgcportwin.cpp(154) : warning C6250: Calling 'VirtualFree' without the MEM_RELEASE flag might free memory but not address descriptors (VADs). This causes address space leaks

This report is based on static analysis, and does not reflect an actual observed failure.

The relevant code is appears below.


bool VMPI_decommitMemory(char *address, size_t size)
{
	bool success = false;
	MEMORY_BASIC_INFORMATION mbi;	
	do {
		VirtualQuery(address, &mbi, sizeof(MEMORY_BASIC_INFORMATION));
		size_t commitSize = size > mbi.RegionSize ? mbi.RegionSize : size;
		success = VirtualFree(address, commitSize, MEM_DECOMMIT) == TRUE;
		address += commitSize;
		size -= commitSize;
	} while(size > 0 && success);
	
	return success;
}

Comment 1

[Tommy Reilly]

This is by design, we reuse the address space.   We also release address space from GCHeap::Decommit if we have much more than we need.

Comment 2

[William Maddox]

Closed per Tommy's analysis above.

Comment 3

[Trevor Baker]

bulk verifying resolved !fixed issues