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

On Mon, Oct 12, 2009 at 3:03 PM, KOSAKI Motohiro
[off-list ref] wrote:

Hi

Sorry for the delaying.

quoted

On Sat, Oct 10, 2009 at 2:32 AM, KOSAKI Motohiro
[off-list ref] wrote:

quoted

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It does seem like a maximum spin count should be put in there - and
maybe a timeout as well (since with FUSE etc it's possible to engineer
page faults that take arbitrarily long).
Also, it occurs to me that:

makes sense.
I like maximum spin rather than timeout.

I'm worried about the scenario where process A sets its cmdline buffer
to point to a page which will take a _VERY_ long time to pagein (maybe
forever), and then process B goes to try to read its cmdline. What
happens now?

Honestly, I don't worry about so much. if attacker want DoS attack, fork bomb is
efficient than this way. then, attacker never use this.

Fork bombs and etc can be mitigated by resource limits; but if the
command line is placed on a page that will take a very long time to
fault, then that cannot be mitigated... But again, this DoS already
exists and isn't any easier with this patch, so I think it's a
separate issue.

quoted

Process A can arrange for this to happen by using a FUSE filesystem
that sits on a read forever. And since the first thing the admin's
likely to do to track down the problem is 'ps awux', this is liable to
be a rather nasty DoS...

Probably, I haven't understand this paragraph. Why is this FUSE related issue?

Just an example of how one can create a page that will take a very
long time to fault in.