oss-security - Re: screen crash processing combining characters

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Date: Tue, 9 Feb 2021 18:11:37 -0000 (UTC)
From: Tavis Ormandy <taviso@...il.com>
To: oss-security@...ts.openwall.com
Subject: Re: screen crash processing combining characters

On 2021-02-09, Harry Sintonen wrote:
> On Tue, 9 Feb 2021, Tavis Ormandy 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 managed to reproduce this against screen + irssi. It was a bit tricky to 
> get it triggered but eventually screen did die.
>

welp, I minimized it a bit and it crashed xterm too.

I minimized it to 772 characters:

$ wc -m input.txt
772 input.txt

Here is the minimized version (gzipped and base64 encoded to avoid
crashing anything anybody's mail client).

$ gzip -9c < input.txt | base64
H4sIAD7OImACA02W61IiQQyFX10WpkdZF5QFF4TVWbkoKpcZVuQyMM/iD99DTPM1p4qiTp1O0klO
OvDp3Mf3p/gsio+4ZqB9+D4ybm+gJ8y7gesTEyffwG2EiQ3ci9fGwOLERAsDffGaGYiFiQx0JE6O
TZk4SwOZePmjW/F6MZAK4yO/ideVAani2JZ/wpwZOBMvqyIuhHkyUDkyriRHXUDJjoLXOyASY+v8
3gnTImf0igriwBzb8io5Nw2MyWcoR3PA1EBZ1EkN5GJsKhdbYTpoGm7/YeBScm7S1T1MRg8HeFWs
UumhuwDcAcJkmtyuivEf8fLzox0b0I2EozLqbC3OCuMZ/dnB1CVyDHglsu/Pi9wVUu1RYELkcORn
Yy2Rn+3S/8JcERB1Ij/zN3LXFr3GMI8GErE5N9CE2RD5r9j4V6m3twBv2Pj3VZPZ2DO0QfcbA12J
7BW8E8bvjQl9Hsilv7CZACygzacxD4CUQRqJe8MAUrowCQdQZyA98yz5FGySDu5N5jDU1ebtRHhV
AHVsJlyxgumicninGVO3wX3MZI643XdM1oVL2S1hP484eiB53425ePWR2yHTBCY8qyXTkhI5533l
yH3BFvXlhL0RhOtjc9iQJfLJ2VGMsTfe70SdMOENbPz0NkQd/4iepC5qjzsw57Qu6JWRD5XGbZIP
PRwaCAukTM6J5LxArwSmxLYJHXN0w/GIlhj/BqzYkFu8PDOVugYoWGPBZjTzDuAv/SlvOeLSUPsQ
Y0bUrQ084tU7lRORz3GBzFlxGe4t8WInxGu8qsw8izGuMhJlNm1KOSHDW+6ih+7SwFK6ERK7ZoEs
sLE4Lvw92InXPerk5DNlfixDJz8K0ZxGxSg484P6Be3RyjwMCQAA

To reproduce in XTerm, decode the file then try to select the line.

I'll send a report to Thomas Dickey.

Tavis.

-- 
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 /\\  _o)  _o)  $ finger taviso@....org
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