[Bug 1327268] Re: sudo-ldap segfaults in 14.04 if ldap is being used

[Raubvogel]

I talked to Todd C. Miller, the author of sudo, who proposed the
following patch:

diff -r 6c0cc2def911 plugins/sudoers/ldap.c
--- a/plugins/sudoers/ldap.c    Wed Jun 04 11:43:39 2014 -0600
+++ b/plugins/sudoers/ldap.c    Mon Jun 16 13:41:02 2014 -0600
@@ -2429,10 +2429,11 @@
        rc = ldap_sasl_interactive_bind_s(ld, ldap_conf.binddn, "GSSAPI",
            NULL, NULL, LDAP_SASL_QUIET, sudo_ldap_sasl_interact, auth_id);
        if (new_ccname != NULL) {
-           rc = sudo_set_krb5_ccache_name(old_ccname, NULL);
+           rc = sudo_set_krb5_ccache_name(old_ccname ? old_ccname : "", NULL);
            if (rc == 0) {
                sudo_debug_printf(SUDO_DEBUG_INFO|SUDO_DEBUG_LINENO,
-                   "restore ccache name %s -> %s", new_ccname, old_ccname);
+                   "restore ccache name %s -> %s", new_ccname,az
+                   old_ccname ? old_ccname : "(none)");
            } else {
                sudo_debug_printf(SUDO_DEBUG_WARN|SUDO_DEBUG_LINENO,
                    "gss_krb5_ccache_name() failed: %d", rc);

We tested it in my 14.04LTS amd64 (sudo 1.8.9p5) install and that solved
the problem. The above patch will be incorporated in the next version of
sudo. But, I am posting it here in case someone wants to backport it to
the sudo 1.8.9 ubuntu package

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https://bugs.launchpad.net/bugs/1327268

Title:
  sudo-ldap segfaults in 14.04 if ldap is being used

Status in “sudo” package in Ubuntu:
  New

Bug description:
  NOTE: I was asked in
  https://answers.launchpad.net/ubuntu/+source/sudo/+question/249819 to
  report this as a bug.

  raub at testfirewall:~$ lsb_release -a
  No LSB modules are available.
  Distributor ID: Ubuntu
  Description: Ubuntu 14.04 LTS
  Release: 14.04
  Codename: trusty
  raub at testfirewall:~$ uname -a
  Linux testfirewall 3.13.0-27-generic #50-Ubuntu SMP Thu May 15 18:06:16 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
  raub at testfirewall:~$

  and have before upgrading to 14.04 been using sudo-ldap so network
  admins can do some work. However, in 14.04, I am seeing

  raub at testfirewall:~$ sudo pwd
  sudo: LDAP Config Summary
  sudo: ===================
  sudo: uri ldap://kdc.domain.com ldap://kdc2.domain.com
  sudo: ldap_version 3
  sudo: sudoers_base ou=SUDOers,dc=domain,dc=com
  sudo: binddn (anonymous)
  sudo: bindpw (anonymous)
  sudo: bind_timelimit 3
  sudo: timelimit 3
  sudo: deref 0
  sudo: ssl start_tls
  sudo: tls_cacertfile /etc/ssl/certs/ca-certificates.crt
  sudo: use_sasl yes
  sudo: sasl_auth_id (NONE)
  sudo: rootuse_sasl -1
  sudo: rootsasl_auth_id (NONE)
  sudo: sasl_secprops (NONE)
  sudo: krb5_ccname FILE:/tmp/host.tkt
  sudo: ===================
  sudo: ldap_set_option: debug -> 0
  sudo: ldap_set_option: tls_cacertfile -> /etc/ssl/certs/ca-certificates.crt
  sudo: ldap_set_option: tls_cacert -> /etc/ssl/certs/ca-certificates.crt
  sudo: ldap_initialize(ld, ldap://kdc.domain.com ldap://kdc2.domain.com)
  sudo: ldap_set_option: ldap_version -> 3
  sudo: ldap_set_option: timelimit -> 3
  sudo: ldap_set_option(LDAP_OPT_TIMEOUT, 3)
  sudo: ldap_set_option(LDAP_OPT_NETWORK_TIMEOUT, 3)
  sudo: ldap_start_tls_s() ok
  sudo: sudo_ldap_sasl_interact: SASL_CB_USER
  Segmentation fault (core dumped)

  raub at testfirewall:~$

  From syslog:
  Jun 5 15:16:26 testfirewall kernel: [2068248.457275] sudo[22925]: segfault at 0 ip 00007f2feb02692a sp 00007ffff55073b8 error 4 in libc-2.19.so[7f2feaf9d000+1bc000]

  That affects both local and network users *and* was observed in a new
  install and an upgrade from 12.04LTS. Now, if I disable ldap for
  sudoers in /etc/nsswitch.conf,

  # sudoers: files ldap
  sudoers: files

  I can sudo from a local user with sudo rights. What am I missing here?

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