Re: possible su local D.o.S

[Flavio Veloso <flaviovs () magnux com>]

On Thu, 13 Dec 2001, H VC wrote:

Did you ever tried the command below?

    $ perl -e 'print "A" x 100000000' > /dev/null

> Hi,
>
> Dave Ahmad ( da () securityfocus com ) tell me to post this.
>
> On a default installation of RedHat 7.2 sh-utils-2.0.11-5 is installed. On a
> RH 7.1 sh-utils version is 2.0.13 ... ¿ Why this ?
>
> On my RH 7.2 I tried this :
>
> [hvc@condor hvc] $ su `perl -e 'print "A" x 100000000'`
>
> and my box got practically frozen.
> I'm on a K6-II 500 , 128 MB and 550 of swap.
>
> I have noticed that it only seems to work whe I parse a user string
> to su near the limit ( free mem. + swap ). Over this range is detected
> as a too many large string but also just over the available memory...
>
> Why su allows so large user names ?
> How long could be a unix/linux user name ?
> Why do not su limit the size of username to the unix/linux max. size of a
> user name ?
>
> Thanks.
>
> HVC
>
> Hugo Vázquez Caramés
> IT Security Services Winmat
> Barcelona
> Spain
>
> overclocking_a_la_abuela () hotmail com
>
>
>
>
>
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-- 
Flávio