Thread (27 messages) 27 messages, 7 authors, 2010-02-11

Re: [PATCH] Restrict initial stack space expansion to rlimit

From: Michael Neuling <hidden>
Date: 2010-02-10 05:30:16
Also in: linux-fsdevel, lkml


In message [ref] you wrote:
quoted
On 02/09/2010 10:51 PM, Michael Neuling wrote:
quoted
quoted
quoted
I'd still like someone with a CONFIG_STACK_GROWSUP arch to test/ACK it
as well.
There's only one CONFIG_GROWSUP arch - parisc.
Could someone please test it on parisc?
I did.
quoted
How about doing:
   'ulimit -s 15; ls'
before and after the patch is applied.  Before it's applied, 'ls' should
be killed.  After the patch is applied, 'ls' should no longer be killed.

I'm suggesting a stack limit of 15KB since it's small enough to trigger
20*PAGE_SIZE.  Also 15KB not a multiple of PAGE_SIZE, which is a trickier
case to handle correctly with this code.

4K pages on parisc should be fine to test with.
Mikey, thanks for the suggested test plan.

I'm not sure if your patch does it correct for parisc/stack-grows-up-case.

I tested your patch on  a 4k pages kernel:
root@c3000:~# uname -a
Linux c3000 2.6.33-rc7-32bit #221 Tue Feb 9 23:17:06 CET 2010 parisc GNU/Li
nux
quoted
Without your patch:
root@c3000:~# ulimit -s 15; ls
Killed
-> correct.

With your patch:
root@c3000:~# ulimit -s 15; ls
Killed
_or_:
root@c3000:~# ulimit -s 15; ls
Segmentation fault
-> ??

Any idea?
My x86_64 box also makes segmentation fault. I think "ulimit -s 15" is too sm
all stack for ls.
"ulimit -s 27; ls "  wroks perfectly fine.
Arrh.  I asked Helge offline earlier to check what use to work on parisc
on 2.6.31.

I guess PPC has a nice clean non-bloated ABI :-D

Mikey
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