Re: [Full-disclosure] GNU libc/regcomp(3) Multiple Vulnerabilities

[halfdog <me@xxxxxxxxxxx>]

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aksymilian Arciemowicz wrote:
> [ GNU libc/regcomp(3) Multiple Vulnerabilities ]
> 
> Author: Maksymilian Arciemowicz
> http://securityreason.com/
> http://cxib.net/
> Date:
> - Dis.: 01.10.2010
> - Pub.: 07.01.2011
> 
> CERT: VU#912279
> CVE:
> CVE-2010-4051
> CVE-2010-4052

Nice find, but not the first one, look at:

https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/343894

I just reported the issue to ubuntu so see how their bug tracking team
was performing on an issue where a standard byte-array-fuzzer just
needed 2secs to find it. I wanted to know, if they could detect a
misclassified issue (was not reported as security bug) and bring it to a
fix. I would have bet, that they would be faster than you, but it seems
that you made the race. What I learned from the excercise (see bug
report date March 2009), is that the ubuntu launchpad platform is an
invaluable source of exploits when used together with google mining.

As to the regexes: If you want to start collecting CVEs, many other
programs are also vulnerable to regex resource exhaustion, e.g. using
postgres extended regulars.

As for the segfaults: The problem with memory-allocation errors is quite
common in many programs and not only restricted to regular expressions.
Even many suid-binaries have quite funny behavior when limiting
resources, e.g. to trigger null-pointer deref in sudoedit on lucid,

(gdb) bt
#0  __tsearch (key=0xbfb3e4e0, vrootp=0x1c, compar=0xb14490 <known_compare>)
    at tsearch.c:251
#1  0x00b1407e in *__GI___nss_lookup_function (ni=0x0,
    fct_name=0xb691bb "setpwent") at nsswitch.c:342

See http://www.halfdog.net/Security/LowMemoryProgramCrashing/


- -- 
http://www.halfdog.net/
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