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Date: Tue, 9 Feb 2021 16:06:07 -0000 (UTC)
From: Tavis Ormandy <taviso@...il.com>
To: oss-security@...ts.openwall.com
Subject: screen crash processing combining characters
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]->prev = i;
1417 combchars[i]->next = i;
1418 }
Exploitable or not, it would be annoying if someone stuffed this into logfiles
being tailed, or whatever.
Tavis.
--
_o) $ lynx lock.cmpxchg8b.com
/\\ _o) _o) $ finger taviso@....org
_\_V _( ) _( ) @taviso
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