[Study] Ascending Stack Vs. Descending Stack

Study/Computer Science 2007.02.07 15:09

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Ascending Stack : The stack grows upwards, starting from a low address and progressing to a higher address.
Descending Stack : The stack grows downwards, starting with a high address and progressing to a lower one.

Fundamentally, these two are same. But, I prefer descending stack, because when stack is broken, mostly post-stack-section(higher memory address) tends to be broken. So,

- [case1 : current stack has enough free space]
Descending stack is better to detect stack-corruption than ascending stack.

void func_test(void)
{
    (omitted...)
    char a[10]; // ---(*1)
    (omitted...)
    memcpy(a, data, len); // len > 10 ---(*2)
   (omitted...)
}

If stack space after (*1) is not used, then even if stack is corrupted, it is very difficult to detect in ascending stack.
(because, no one uses corrupted area.) So, debugging is more difficult.

- [case2 : current stack is almost pull]
In descending stack, usually, corrupting stack of specific thread(Thread A) affects it's own behavior firstly. So, it is easier to debug - same with [case1].
In ascending stack, corrupting stack may affects to other thread's stack - thread whose stack is just next (higher address) of Thread A - firstly with high possibility (especially, if several stacks are adjacent in memory space). This usually leads to debugging-nightmare

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