Code:  static int gss_iakerbmechglue_init(void)
 {
     struct gss_mech_config mech_iakerb;
    struct gss_config iakerb_mechanism = krb5_mechanism;
    /* IAKERB mechanism mirrors krb5, but with different context SPIs */
    iakerb_mechanism.gss_accept_sec_context = iakerb_gss_accept_sec_context;
    iakerb_mechanism.gss_init_sec_context   = iakerb_gss_init_sec_context;
    iakerb_mechanism.gss_delete_sec_context = iakerb_gss_delete_sec_context;
    iakerb_mechanism.gss_acquire_cred       = iakerb_gss_acquire_cred;
    iakerb_mechanism.gssspi_acquire_cred_with_password
                                    = iakerb_gss_acquire_cred_with_password;
 
     memset(&mech_iakerb, 0, sizeof(mech_iakerb));
     mech_iakerb.mech = &iakerb_mechanism;

    mech_iakerb.mechNameStr = "iakerb";
    mech_iakerb.mech_type = (gss_OID)gss_mech_iakerb;
    gssint_register_mechinfo(&mech_iakerb);

    return 0;
}

Vulnerability Type: DoS 
CWE ID: CWE-18
Summary: lib/gssapi/krb5/iakerb.c in MIT Kerberos 5 (aka krb5) before 1.14 relies on an inappropriate context handle, which allows remote attackers to cause a denial of service (incorrect pointer read and process crash) via a crafted IAKERB packet that is mishandled during a gss_inquire_context call.
Commit Message: Fix IAKERB context aliasing bugs [CVE-2015-2696]

The IAKERB mechanism currently replaces its context handle with the
krb5 mechanism handle upon establishment, under the assumption that
most GSS functions are only called after context establishment.  This
assumption is incorrect, and can lead to aliasing violations for some
programs.  Maintain the IAKERB context structure after context
establishment and add new IAKERB entry points to refer to it with that
type.  Add initiate and established flags to the IAKERB context
structure for use in gss_inquire_context() prior to context
establishment.

CVE-2015-2696:

In MIT krb5 1.9 and later, applications which call
gss_inquire_context() on a partially-established IAKERB context can
cause the GSS-API library to read from a pointer using the wrong type,
generally causing a process crash.  Java server applications using the
native JGSS provider are vulnerable to this bug.  A carefully crafted
IAKERB packet might allow the gss_inquire_context() call to succeed
with attacker-determined results, but applications should not make
access control decisions based on gss_inquire_context() results prior
to context establishment.

    CVSSv2 Vector: AV:N/AC:M/Au:N/C:N/I:N/A:C/E:POC/RL:OF/RC:C

[ghudson@mit.edu: several bugfixes, style changes, and edge-case
behavior changes; commit message and CVE description]

ticket: 8244
target_version: 1.14
tags: pullup