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

From: richard -rw- weinberger
Date: Fri Aug 03 2012 - 07:30:25 EST


On Fri, Aug 3, 2012 at 1:27 PM, Cyrill Gorcunov <gorcunov@xxxxxxxxxx> wrote:
> On Fri, Aug 03, 2012 at 01:19:24PM +0200, richard -rw- weinberger wrote:
>> >>
>> >> 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.
>
> Look, the /proc entry might check for some CAP and do not allow
> a regular user to fetch this address.

We could also add another check to get_robust_list().
It does already ptrace_may_access().

--
Thanks,
//richard
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