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Date: Fri, 29 Apr 2016 12:13:08 -0400 (EDT)
From: cve-assign@...re.org
To: mprpic@...hat.com
Cc: cve-assign@...re.org, oss-security@...ts.openwall.com
Subject: Re: CVE request: three issues in libksba

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> Denial of Service due to stack overflow in src/ber-decoder.c
> http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libksba.git;a=commit;h=07116a314f4dcd4d96990bbd74db95a03a9f650a

Use CVE-2016-4353. (This CVE is about changing the type of error
handling after a decoder stack overflow. It is not about changing the
decoder so that a decoder stack overflow occurs in fewer cases.)


> Integer overflow in the BER decoder src/ber-decoder.c
> http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libksba.git;a=commit;h=aea7b6032865740478ca4b706850a5217f1c3887

>> The actual bug described below is due to assigning an int
>> (val.length) to a size_t (ti.length). The int was too large and thus
>> negative so that the condition to check for too large objects didn't
>> worked. Changing the type would have been enough but other conditions
>> are possible. Thus the introduction of sum_a1_a2_ge_b for overflow
>> checking and checks when adding 100 extra bytes to malloc calls are
>> added.

We consider this two separate issues.

Use CVE-2016-4354 for the use of an incorrect integer data type.

Use CVE-2016-4355 for the cases in which the code was simply making no
attempt to check for an integer overflow (the "+ 100" cases and the
"+= d->val.length" case).


> Integer overflow in the DN decoder src/dn.c
> http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libksba.git;a=commit;h=243d12fdec66a4360fbb3e307a046b39b5b4ffc3

This might be an error in the original
https://security.gentoo.org/glsa/201604-04 advisory. We did not notice
any obvious relationship between
243d12fdec66a4360fbb3e307a046b39b5b4ffc3 and an integer overflow fix.
The 243d12fdec66a4360fbb3e307a046b39b5b4ffc3 commit message seems to
focus on "read access out of bounds." Also, there is no other recent
commit at
http://git.gnupg.org/cgi-bin/gitweb.cgi?p=libksba.git;a=history;f=src/dn.c
that refers to an integer overflow. Possibly there was an inapplicable
copy-and-paste of "Integer overflow in the" from the previous report
about the BER decoder.

Use CVE-2016-4356 for the 243d12fdec66a4360fbb3e307a046b39b5b4ffc3
issue that is described as "Fix encoding of invalid utf-8 strings in
dn.c" and "read access out of bounds."

- -- 
CVE Assignment Team
M/S M300, 202 Burlington Road, Bedford, MA 01730 USA
[ A PGP key is available for encrypted communications at
  http://cve.mitre.org/cve/request_id.html ]
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