From: erik quanstrom <quanstro@quanstro.net>
To: 9fans@9fans.net
Subject: Re: [9fans] crashing plan9 source boot CD with key combination (buffer overflow)
Date: Fri, 20 Jun 2014 08:10:29 -0400 [thread overview]
Message-ID: <9a790dee571c2ece4b126c12bd940ea1@brasstown.quanstro.net> (raw)
In-Reply-To: <C83193F6-E621-42B5-86D2-42607D1FF40B@fb.com>
On Fri Jun 20 06:24:25 EDT 2014, pad@fb.com wrote:
good catch, but...
> The code in kbdputsc() in kbd.c does not look very safe:
>
> kbscan->kc[kbscan->nk++] = c; <--------- no bound checking, can overflow.
this behavior depends entirely on what latin1() does. if
latin1() will always consume the array before kbscan->nk reaches
some bound, then extra checking here wouldn't change anything.
and that's the case. (read port/latin1.c for details).
the real problem is that kc should be strlen("x10ffff") = 7.
(sources is wrong here, too, UTFmax*2+1 = 9, which would
allow for x1000ffff, which is not a rune)
- erik
ps: the bug was introduced here
Apr 30 16:05:23 EDT 2013 /n/sourcesdump/2014/0620/plan9/sys/src/9/port/latin1.c 1570
pps: 9atom patch applied /n/atom/patch/applied/collectlen
prev parent reply other threads:[~2014-06-20 12:10 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-20 10:22 Yoann Padioleau
2014-06-20 12:10 ` erik quanstrom [this message]
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