Date: Tue, 7 May 2013 04:56:04 -0400 (EDT) From: Jan Lieskovsky <jlieskov@...hat.com> To: "Eric S. Raymond" <esr@...rsus.com> Cc: Kurt Seifried <kseifried@...hat.com>, "Steven M. Christey" <coley@...us.mitre.org>, Miroslav Lichvar <mlichvar@...hat.com>, oss-security@...ts.openwall.com Subject: Re: CVE Request -- gpsd 3.9 fixing a denial of service flaw Hello Eric, since there have doubts appeared: https://bugs.mageia.org/show_bug.cgi?id=9969#c2 which upstream patch has been the CVE-2013-2038 identifier assigned to, could you confirm / disprove the latter? * The true crash was in the NMEA(2000) driver, with upstream patch: http://git.savannah.gnu.org/cgit/gpsd.git/commit/?id=dd9c3c2830cb8f8fd8491ce68c82698dc5538f50 This one should be referenced under CVE-2013-2038. * While the hypothetical one was in the AIS driver, with upstream patch: http://git.savannah.gnu.org/cgit/gpsd.git/commit/?id=08edc49d8f63c75bfdfb480b083b0d960310f94f Upstream 3.9 announcement "Armor the AIS driver against an implausible overrun attack." would support this. Thank you for your time && Regards, Jan. -- Jan iankko Lieskovsky / Red Hat Security Response Team ----- Original Message ----- > From: "Jan Lieskovsky" <jlieskov@...hat.com> > To: esr@...rsus.com, "Kurt Seifried" <kseifried@...hat.com> > Cc: "Steven M. Christey" <coley@...us.mitre.org>, "Miroslav Lichvar" <mlichvar@...hat.com>, > oss-security@...ts.openwall.com > Sent: Friday, May 3, 2013 6:31:08 PM > Subject: Re: [oss-security] CVE Request -- gpsd 3.9 fixing a denial of service flaw > > > Thank you for your time && reply, Eric. > > ----- Original Message ----- > > From: "Eric S. Raymond" <esr@...rsus.com> > > To: "Kurt Seifried" <kseifried@...hat.com> > > Cc: oss-security@...ts.openwall.com, "Jan Lieskovsky" > > <jlieskov@...hat.com>, "Steven M. Christey" > > <coley@...us.mitre.org>, "Miroslav Lichvar" <mlichvar@...hat.com> > > Sent: Thursday, May 2, 2013 9:41:51 PM > > Subject: Re: [oss-security] CVE Request -- gpsd 3.9 fixing a denial of > > service flaw > > > > Kurt Seifried <kseifried@...hat.com>: > > > On 05/02/2013 03:58 AM, Jan Lieskovsky wrote: > > > > @Eric - Eric, could you please help us to solve this doubt? (which > > > > of the patches is the correct one to fix the above mentioned DoS / > > > > security issue) > > > > There are two critical patches which solve two different DoSes (well, > > one certain and one potential). Yes, it's a strange coincidence that > > both bugs were characterized at almost the same time after we haven't > > had a crash bug since 2007. > > > > The crash bug was in the NMEA driver. There's particular kind of malformed > > packet, sometimes emitted by SiRFStar-III receivers, that looks like this: > > > > $GPGGA,030130$GPGLL,2638.1728,N,08011.3893,W,030131.000,A,A*41\r\n > > > > See the incomplete GGA without trailing \r\n at the front? Usually > > that was harmless and would be silently discarded. Under rare circumstances > > it could core dump (but not any more, I now have a regression test to check > > this case). > > > > That fix was commit dd9c3c2830cb8f8fd8491ce68c82698dc5538f50. > > So this is observed / experienced DoS, right? Kurt, assuming the > CVE-2013-2038 identifier: > http://www.openwall.com/lists/oss-security/2013/05/02/17 > > has been assigned to this sub-case, correct? > > > > > The potential crash/DoS was in the AIS driver. > > > > The first stage of what it does is un-armor an AIVDM ASCII packet > > representation into an equivalent binary packet which is then examined > > for data at specific bit offsets. > > > > The un-armoring logic was not properly bounds-checked, potentially > > opening up a hole. In theory, an overlong armored packet could be > > crafted to overrun the binary-packet buffer. > > > > I'm not sure that one was exploitable; there are other properties of > > the code (notably the bounds-checked maximum length of the AIVDM ASCII > > packet buffer) that seem to guarantee the end of the binary packet > > buffer could never be reached. > > Meaning this wouldn't be a DoS attack vector? (asking to know if a > separate / second CVE identifier is needed for this case yet, or not) > > > > > I put in a check anyway, because (a) I could be wrong about that, (b) > > supposing I'm right, that invariant could get silently broken by a future > > code change. > > > > That was commit 08edc49d8f63c75bfdfb480b083b0d960310f94f, responding > > to Savannah bug #38511. > > Application of the patch looks reasonable. Just would be good to know > if it was applied just like a preventive measure (no DoS right now, just > prevent its [possible] occurrence in the future in case of code change) > or if under certain circumstances it might be used to DoS gpsd too? > > > > > Note: neither of these have privilege-escalation possibilities. gpsd > > needs root to initialize, but drops it long before either of these > > code defects could fire. > > Ok, good. > > Thank you && Regards, Jan. > -- > Jan iankko Lieskovsky / Red Hat Security Response Team > > > > > If you have any other questions, do not hesitate to ask. > > -- > > <a href="http://www.catb.org/~esr/">Eric S. Raymond</a> > > >
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