Re: RFC: squid: Fix free memory corruption and off-by-on error when comparing SNMP OIDs

[Henrik Nordström <henrik () henriknordstrom net>]

It's just bugs in the snmp initialization code and not considered a
security issue. But the invalid free may result in free heap corruption
(subject to quality of malloc implementation) which may then cause
stability issues later on. Both issues were introduced in 3.1.4 and
found in an project internal code quality audit.

Regards
Henrik Nordström
Squid HTTP Proxy project

fre 2010-08-13 klockan 09:00 +0200 skrev Thomas Biege:
> Hello project maintainers,
> we stumbled over two bugs in your last release because they sound like
> security vulnerabilities. Can you shed some light on them for us please?
>
> Thanks
> Thomas
>
>
> Am Donnerstag, 12. August 2010, 20:58:13 schrieb Josh Bressers:
> > ----- "Thomas Biege" <thomas () suse de> wrote:
> > > Hello people,
> > > does someone know if this bug has security implications. TIA!
> > >
> > > http://www.squid-cache.org/Versions/v3/3.1/changesets/SQUID_3_1_5.html
> > > http://www.squid-cache.org/Versions/v3/3.1/changesets/squid-3.1-10008.pat
> > > ch
> >
> > This is really two flaws. The first bit of the patch is an off by one on
> > the loop that could overflow a heap buffer.
> >
> > From looking at the code, I only see this function being called with static
> > strings for the MIBs. I may be missing something, but it doesn't appear
> > that arbitrary strings make it into this. I'm not sure if this can be
> > exploted, or if it's just a bug someone noticed.
> >
> > The second flaw is an invalid free. I'm not sure if arbitrary data can make
> > it into this, but with current glibc memory protections, this should be a
> > DoS only.
> >
> > Both only seem to affect modern versions of squid. The code seems present
> > in 3.1.4, but not 2.6.STABLE21 (these are two versions we ship).
> >
> > Have you mailed upstream at all?
> >
> > Thanks.