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nicowilliamsgreghudson
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Fix SPNEGO context aliasing bugs [CVE-2015-2695]
The SPNEGO mechanism currently replaces its context handle with the mechanism context 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 SPNEGO context structure after context establishment and refer to it in all GSS methods. Add initiate and opened flags to the SPNEGO context structure for use in gss_inquire_context() prior to context establishment. CVE-2015-2695: In MIT krb5 1.5 and later, applications which call gss_inquire_context() on a partially-established SPNEGO context can cause the GSS-API library to read from a pointer using the wrong type, generally causing a process crash. This bug may go unnoticed, because the most common SPNEGO authentication scenario establishes the context after just one call to gss_accept_sec_context(). Java server applications using the native JGSS provider are vulnerable to this bug. A carefully crafted SPNEGO 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
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Diff for: src/lib/gssapi/spnego/gssapiP_spnego.h

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@@ -103,6 +103,8 @@ typedef struct {
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int firstpass;
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int mech_complete;
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int nego_done;
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int initiate;
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int opened;
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OM_uint32 ctx_flags;
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gss_name_t internal_name;
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gss_OID actual_mech;

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