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Message #01065
[Bug 1326500] Re: libgssapi-krb5-2: segfault when mechglue loops endlessly on call to gss_add_cred_from
With the upload of krb5 1.12.1+dfsg-3ubuntu1 to utopic, this is fixed in
utopic. Any additional help I can provide getting this into trusty?
** Changed in: krb5 (Ubuntu)
Status: Triaged => Fix Released
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https://bugs.launchpad.net/bugs/1326500
Title:
libgssapi-krb5-2: segfault when mechglue loops endlessly on call to
gss_add_cred_from
Status in “krb5” package in Ubuntu:
Fix Released
Status in “krb5” source package in Trusty:
Triaged
Bug description:
There's a bug fixed in krb5 1.12.1+dfsg-2 (just uploaded to Debian) where if a gss-api mechanism is dynamically loaded, and that mechanism uses symbols from libgssapi_krb5, and doesn't provide certain optional entry points added in krb5 1.12, then calling one of those entry points will cause the mechglue to call itself. This results in an endless loop and the process eventually crashes on stack exhaustion.
Unfortunately, one of the entry points, gss_add_cred_from is going to get called quite commonly.
So, this means that if you're using Ubuntu to develop a GSS-API mechanism or are installing a third party gss-api mechanism, things are going to crash, mostly whenever anyone tries to use gss-api as a server, regardless of whether they intended to use your application.
I'd like to see this fixed in trusty, so I'm giving a detailed repro below. Patch against trusty coming shortly.
Apologies that the repro is a bit involved; there's not a mechanism packaged in Ubuntu that easily exhibits this. However, you really ought to be able to use Ubuntu to develop a GSS mechanism without crashing all your gss apps.
On a stock trusty system, first install the attached mech file as
/usr/etc/gss/mech (yes that's /usr/etc, not /etc) and then run the
following:
sudo add-apt-repository ppa:moonshot/daily
sudo apt-get update
4 sudo apt-get install bzr libkrb5-dev libradsec-dev libssl-dev libjansson-dev autoconf automake libtool build-essential
bzr branch -r739 lp:moonshot
cd moonshot/
autoreconf -i
./configure --without-opensaml --without-shibresolver
make -j3
sudo make install
sudo apt-get install krb5-gss-samples
gss-server host@localhost
This will segfault
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