Re: +c-r-prctl-add-ability-to-set-new-mm_struct-exe_file-update-after-mm-num_exe_file_vmas-removal.patch added to -mm tree

[Oleg Nesterov]

On 04/20, Konstantin Khlebnikov wrote:
>
> Oleg Nesterov wrote:
>>
>> You misunderstood. I am not arguing with "one-shot", I do not really
>> care.
>>
>> My question is: unless I missed something "it can't be changed again"
>> is not actually true. A task does PR_SET_MM_EXE_FILE, then it forks
>> the new child. The child can do PR_SET_MM_EXE_FILE again. Is this
>> by design?
>>
>> Oleg.
>>
>
> I found more weird case: child thread (with CLONE_THREAD and without CLONE_VM)
> changes its exe_file...

No. copy_process() does:

	if ((clone_flags & CLONE_THREAD) && !(clone_flags & CLONE_SIGHAND))
		return ERR_PTR(-EINVAL);

	if ((clone_flags & CLONE_SIGHAND) && !(clone_flags & CLONE_VM))
		return ERR_PTR(-EINVAL);

IOW, CLONE_THREAD => CLONE_SIGHAND => CLONE_VM

Oleg.

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