Re: [PATCH v6] Added PR_SET_PROCTITLE_AREA option for prctl()

[Bryan Donlan]

On Tue, Dec 8, 2009 at 12:38 AM, Ingo Molnar <mingo@xxxxxxx> wrote:
>
> * KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> wrote:
>
>> > The feature looks useful, but the choice of a prctl as an API is strange
>> > - it limits us to the current task only - while the ability to set
>> > arguments for another task looks a more generic (and potentially more
>> > useful) solution.
>>
>> No. It's impossible.
>> /proc/{pid}/cmdline read user process's memory. iow, this prctl() don't
>> receive string, it receive virtual address itself. [...]
>
> it's not 'impossible' at all, you yourself mention ptrace:

If another process is going to use ptrace to inject the cmdline string
into the victim's address space, it can also temporarily hijack a
thread to run prctl() on its behalf...
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