[PATCH v2 0/3] posix: Execute file function fixes

[Paul Eggert]

On 02/19/2016 10:05 AM, Adhemerval Zanella wrote:
> * Regarding stack allocation safeness for exec function family I saw no
>    safe solution.

This is a significant regression from the current behavior. We need a 
better solution. Otherwise, I fear that it will be too easy for 
attackers to exploit stack-overflow vulnerabilities by attempting to 
execute commands with many arguments.

>    libc has no obligation in make sure the stack allocation is suffice to
>    fix runtime constraints.

Is this really true?  Then why does libc have __libc_use_alloca? Why not 
dispense with __libc_use_alloca and have libc impose no limits on stack 
allocation?