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Memory leaks are always contained inside processes, aren't they?

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I acknowledge the fact that memory leaks are bad, regardless of if you're doing it on purpose or not.

 

I do notice there's a behavior in memory leaks, such that if a program were to create memory leaks, Windows 7's Task Manager will always show the program's name and process in the list even if the program had already been closed. Same applies to MSBuild for Visual Studios, if the affected program left behind tons of unresolved commands, we kill the process in Task Manager.

 

My guess is that memory leaks are always contained and recollected back into the resource pool when the affected process has been killed by Task Manager. And that there is no way to create a memory leak that is persistent and permanently damaging to the RAM in the computer... am I right in this?

struct Object
{
	int hello;
	bool world;
};

void purposefullyCreateMemoryLeak(){
	Object** ptr = new Object*[200];
	for (int i = 0; i < 200; i++){
		ptr[i] = new Object;
		ptr[i]->hello = 20 - i;
		ptr[i]->world = false;
	}
	//Gracefully return and leave behind memory leak.
	return;
}

They say that hackers can create physical damage to hardware components just by software alone. If they are able to create memory leaks and not make it so that it's impossible to be isolated within a process that had quit, it will be a tough day for a researcher.

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The definition of a memory leak is more than just memory being used and not freeing when it should, it has to do with not having direct access as a developer to that area of memory, ie: a loss of control.

 

Sometimes when you close a program, depending on how that programs closing event was programmed, it will handle memory clean up in some manual way, perhaps there is finalizing/handshaking mechanics that are going on it the background, or its possible that the OS is doing some magic to try and release the memory.

Edited by d4n1

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Most memory leaks are contained within the running process, but some are not, especially, GDI leaks. If you run out of handles, well, you're os might start to act/look strangely.

Neither of them are damaging to memory, but with the second case you will have to reboot your computer.

 

I would be very surprise if hackers could actually manage to break things in a computer nowaday. Maybe through some overclocking hack?(i doubt it)

What 'people say' and what is real is often quite different. Since i can't say for 100% sure that this can't happen, i'll let others step in, but it's doubtfull at best.

 

I remember of one virus, CIH, that could do damage to computers, through changing some bios settings, but it was a long time ago.

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A modern OS keeps track of virtual memory allocated to a process through a page table -- a table that maps chunks of process-owned virtual memory addresses into system-owned physical memory addresses.  The chunks of virtual memory, called pages, can be moved around in physical memory or even swapped out to disk.  When a process is ended by the OS, it destroys the page table, and all of the virtual memory disappears into the æther whence it came.  All the memory leaks get disappeared.

 

It's possible, should a hacker gain elevated privileges, to make certain calls into the OS to gain access to physical memory addresses that could cause physical damage to your system.  That's generally an important reason for binding all physical memory accesses within the OS itself, although there can be exploitable bugs in the OS that can allow the clever hacker to bypass all built-in protections.  Memory leaks are not generally one of those exploits:  they're usually found in stack smashes or crafted inputs.  About the only exploit you can do with a memory leak is a local DOS (denial of service) attack, bringing the system to its knees as the swapper thrashes.

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While you mentioned 'processes' several times, your code showed a function, not a process.

So just to be clear, memory leaks do persist after the function ends.
void purposefullyCreateMemoryLeak()
{
	Object *ptr = new Object;
	return;
}

void funcB()
{
    purposefullyCreateMemoryLeak();
    
    //Memory is still leaked!
    return;
}

void funcA()
{
    funcB();
    
    //Memory is still leaked!
    return;
}

int main()
{
    funcA();
    
    //Memory is still leaked!    

    //Sometime after main() exits (and after the function(s) that originally called main() exits),
    //then the memory will most likely be cleaned up by the operating system.
    return 0;
}
It's considered good practice to clean up after yourself, when programming - though if your code is trying to shut down because something went wrong (i.e. the program is crashing in a controlled manner), leaked resources aren't the end of the world.

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