Re: screen crash processing combining characters

                							

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Re: screen crash processing combining characters

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From: Utkarsh Gupta &lt;utkarsh () debian org&gt;

Date: Wed, 10 Feb 2021 01:12:21 +0530

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Hi,

On Tue, 9 Feb, 2021, 9:39 pm Tavis Ormandy, &lt;taviso () gmail com&gt; wrote:

Hello, I noticed someone posted this to the screen-devel list. I can
reproduce it here, just catting the testcase does crash my screen
session.

https://lists.gnu.org/archive/html/screen-devel/2021-02/msg00000.html

(I think it wasn't supposed to be public, but it is, so better it's
visible to security teams)

It looks like it might be exploitable at first glance, I see a crash
here in encoding.c, because i is out of range.

1411   else if (!combchars[i])
1412     {
1413       combchars[i] = (struct combchar *)malloc(sizeof(struct
combchar));
1414       if (!combchars[i])
1415            return;
1416       combchars[i]-&gt;prev = i;
1417       combchars[i]-&gt;next = i;
1418     }

Exploitable or not, it would be annoying if someone stuffed this into
logfiles
being tailed, or whatever.

Got CVE-2021-26937 assigned for this.

- u

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Current thread:

screen crash processing combining characters Tavis Ormandy (Feb 09)

Re: screen crash processing combining characters Tavis Ormandy (Feb 09)

Re: screen crash processing combining characters Harry Sintonen (Feb 09)

Re: screen crash processing combining characters Tavis Ormandy (Feb 09)

Re: screen crash processing combining characters Tavis Ormandy (Feb 09)
Re: Re: screen crash processing combining characters Utkarsh Gupta (Feb 10)

Re: Re: screen crash processing combining characters Salvatore Bonaccorso (Feb 10)

Re: screen crash processing combining characters Utkarsh Gupta (Feb 09)

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