Bug#1014391: scilab: CVE-2022-30045 incorrect memory handling in ezml support leading to a heap out-of-bounds read

[Sylvestre Ledru]

Le 05/08/2022 à 11:43, Neil Williams a écrit :
> On Mon, 1 Aug 2022 18:25:04 +0200 Sylvestre Ledru <sylvestre at mozilla.com> wrote:
>> Hello,
>>
>> Le 05/07/2022 à 11:19, Neil Williams a écrit :
>>> Source: scilab
>>> Version: 6.1.1+dfsg2-3
>>> Severity: important
>>> Tags: security
>>> X-Debbugs-Cc: codehelp at debian.org, Debian Security Team <team at security.debian.org>
>>>
>>> Hi,
>>>
>>> The following vulnerability was published for scilab.
>>>
>>> CVE-2022-30045[0]:
>>> | An issue was discovered in libezxml.a in ezXML 0.8.6. The function
>>> | ezxml_decode() performs incorrect memory handling while parsing
>>> | crafted XML files, leading to a heap out-of-bounds read.
>>>
>>>
>>> If you fix the vulnerability please also make sure to include the
>>> CVE (Common Vulnerabilities & Exposures) id in your changelog entry.
>>>
>>> For further information see:
>>>
>>> [0] https://security-tracker.debian.org/tracker/CVE-2022-30045
>>>       https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-30045
>>>
>>> Please adjust the affected versions in the BTS as needed.
>>>
>>
>> While Scilab indeed ships ezxml.c, I am not sure how this can be exploited.
>>
>> The code is probably only used to load scicos/xcos schema.
>> https://github.com/scilab/scilab/blob/b0937f19e4b8ddf416ca9a9a433bcbbd3f4ef2c0/scilab/modules/scicos/src/c/ezxml.c
>>
> Am I right in thinking that XCOS Schema can be provided by third-parties/users?
> ( https://github.com/scilab/scilab/blob/master/scilab/contrib/xcos_toolbox_skeleton/help/en_US/available_blocks.xml )
>
> What would the effect be of a crash during parsing a corrupt XCOS Schema loaded via a help file, for example?
>
>
>
I think the XML parsing is done elsewhere

But anyway, I proposed a fix upstream:

https://gitlab.com/scilab/scilab/-/merge_requests/1

Cheers

S