Re: [PATCH v2] futex: mark get_robust_list as deprecated

From: richard -rw- weinberger
Date: Fri Aug 03 2012 - 07:19:25 EST


On Fri, Aug 3, 2012 at 1:02 PM, Cyrill Gorcunov <gorcunov@xxxxxxxxxx> wrote:
>> >> I'm using this system call in an application and noticed that's marked
>> >> as deprecated now.
>> >> My application collects all kind of information from crashing programs.
>> >> It's installed in /proc/sys/kernel/core_pattern.
>> >>
>> >> If program X is crashing it executes get_robust_list(X) to get the
>> >> address of the robust list
>> >> and reads the list from /proc/X/mem.
>> >>
>> >> Is there another way to get the robust list from another program (by it's pid)?
>> >
>> > The folks doing checkpoint/restart claim to not need this, so there
>> > might be a way either that or they just haven't hit this problem yet.
>> >
>> > What you are doing sounds like a reasonable use of get_robust_list to me.
>> >
>>
>> CRIU folks, how do you deal with futex robust lists?
>
> Well, I believe we were over-optimistic in claiming that we don't need this
> syscall (to be fair I think we simply yet not faced the problem Eric points).
> So we need some way to fetch this address and set it back. If get_robust_list
> get deprecated maybe we could print it out in /proc/pid/stat or something?

Kees, you said get_robust_list() can be used to bypass ASLR.
How? What makes it worse than /proc/pid/maps?

If the robust list address itself is bad, removing get_robust_list()
and putting the
information into /proc is useless.

--
Thanks,
//richard
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