[PATCH 0/1] sys_setrlimit: make sure ->rlim_max never grows

[Oleg Nesterov <oleg@redhat.com>]

On 09/03, Jiri Slaby wrote:
>
> On 09/02/2009 11:51 PM, Oleg Nesterov wrote:
> > On 09/02, Jiri Slaby wrote:
> >> I can't think of anything else than doing all the checks and updates
> >> under alloc_lock, introducing coarse grained static mutex in setrlimit
> >> to protect it,
> >
> > Oh, please don't ;)
> >
> > Or I missed your point?
> >
> > But if you mean this series, then yes, I agree.
>
> Yes, I meant those. But I don't know what do you agree with :).

Not sure what I agree with, but I am glad we seem to agree with each other ;)

> > We should try to do something
> > to ensure that at least rlim_max can be always lowered when admin writes to
> > /proc/pid/limits.
>
> Yes, that's what I asked about when I wrote the three options which I
> was able to think of above. So any other ideas about how to elegantly
> protect against sys_setrlimit vs. admin+/proc/*/limits race?

Perhaps we should start these change with this patch (see the next email) ?

Perhaps, before your changes, we should "fix" sys_setrlimit() first ?
Well, the patch (the next email) is not tested... What do you think?

Oleg.