krb5: fix CVE-2015-2695

lib/gssapi/spnego/spnego_mech.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 SPNEGO packet that is mishandled during
a gss_inquire_context call.

Backport upstream commit to fix it:
https://github.com/krb5/krb5/commit/b51b33f2bc5d1497ddf5bd107f791c101695000d

Signed-off-by: Wenzong Fan <wenzong.fan@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>

2 files changed, 573 insertions, 0 deletions

diff --git a/meta-oe/recipes-connectivity/krb5/krb5/Fix-SPNEGO-context-aliasing-bugs-CVE-2015-2695.patch b/meta-oe/recipes-connectivity/krb5/krb5/Fix-SPNEGO-context-aliasing-bugs-CVE-2015-2695.patch
new file mode 100644
index 0000000000..227e6c614f
--- /dev/null
+++ b/meta-oe/recipes-connectivity/krb5/krb5/Fix-SPNEGO-context-aliasing-bugs-CVE-2015-2695.patch
@@ -0,0 +1,572 @@
+From 884913e807414a1e06245918dea71243c5fdd0e6 Mon Sep 17 00:00:00 2001
+From: Nicolas Williams <nico@twosigma.com>
+Date: Mon, 14 Sep 2015 12:27:52 -0400
+Subject: [PATCH 1/4] 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
+
+Backport upstream commit:
+https://github.com/krb5/krb5/commit/b51b33f2bc5d1497ddf5bd107f791c101695000d
+
+Upstream-Status: Backport
+---
+ src/lib/gssapi/spnego/gssapiP_spnego.h |   2 +
+ src/lib/gssapi/spnego/spnego_mech.c    | 254 ++++++++++++++++++++++++---------
+ 2 files changed, 192 insertions(+), 64 deletions(-)
+
+diff --git a/src/lib/gssapi/spnego/gssapiP_spnego.h b/src/lib/gssapi/spnego/gssapiP_spnego.h
+index bc23f56..8e05736 100644
+--- a/src/lib/gssapi/spnego/gssapiP_spnego.h
++++ b/src/lib/gssapi/spnego/gssapiP_spnego.h
+@@ -102,6 +102,8 @@ typedef struct {
+ 	int firstpass;
+ 	int mech_complete;
+ 	int nego_done;
++	int initiate;
++	int opened;
+ 	OM_uint32 ctx_flags;
+ 	gss_name_t internal_name;
+ 	gss_OID actual_mech;
+diff --git a/src/lib/gssapi/spnego/spnego_mech.c b/src/lib/gssapi/spnego/spnego_mech.c
+index f9248ab..3423f22 100644
+--- a/src/lib/gssapi/spnego/spnego_mech.c
++++ b/src/lib/gssapi/spnego/spnego_mech.c
+@@ -101,7 +101,7 @@ static OM_uint32 get_negotiable_mechs(OM_uint32 *, spnego_gss_cred_id_t,
+ 				      gss_cred_usage_t, gss_OID_set *);
+ static void release_spnego_ctx(spnego_gss_ctx_id_t *);
+ static void check_spnego_options(spnego_gss_ctx_id_t);
+-static spnego_gss_ctx_id_t create_spnego_ctx(void);
++static spnego_gss_ctx_id_t create_spnego_ctx(int);
+ static int put_mech_set(gss_OID_set mechSet, gss_buffer_t buf);
+ static int put_input_token(unsigned char **, gss_buffer_t, unsigned int);
+ static int put_mech_oid(unsigned char **, gss_OID_const, unsigned int);
+@@ -439,7 +439,7 @@ check_spnego_options(spnego_gss_ctx_id_t spnego_ctx)
+ }
+ 
+ static spnego_gss_ctx_id_t
+-create_spnego_ctx(void)
++create_spnego_ctx(int initiate)
+ {
+ 	spnego_gss_ctx_id_t spnego_ctx = NULL;
+ 	spnego_ctx = (spnego_gss_ctx_id_t)
+@@ -462,6 +462,8 @@ create_spnego_ctx(void)
+ 	spnego_ctx->mic_rcvd = 0;
+ 	spnego_ctx->mech_complete = 0;
+ 	spnego_ctx->nego_done = 0;
++	spnego_ctx->opened = 0;
++	spnego_ctx->initiate = initiate;
+ 	spnego_ctx->internal_name = GSS_C_NO_NAME;
+ 	spnego_ctx->actual_mech = GSS_C_NO_OID;
+ 
+@@ -627,7 +629,7 @@ init_ctx_new(OM_uint32 *minor_status,
+ 	OM_uint32 ret;
+ 	spnego_gss_ctx_id_t sc = NULL;
+ 
+-	sc = create_spnego_ctx();
++	sc = create_spnego_ctx(1);
+ 	if (sc == NULL)
+ 		return GSS_S_FAILURE;
+ 
+@@ -644,10 +646,7 @@ init_ctx_new(OM_uint32 *minor_status,
+ 		ret = GSS_S_FAILURE;
+ 		goto cleanup;
+ 	}
+-	/*
+-	 * The actual context is not yet determined, set the output
+-	 * context handle to refer to the spnego context itself.
+-	 */
++
+ 	sc->ctx_handle = GSS_C_NO_CONTEXT;
+ 	*ctx = (gss_ctx_id_t)sc;
+ 	sc = NULL;
+@@ -1088,16 +1087,11 @@ cleanup:
+ 	}
+ 	gss_release_buffer(&tmpmin, &mechtok_out);
+ 	if (ret == GSS_S_COMPLETE) {
+-		/*
+-		 * Now, switch the output context to refer to the
+-		 * negotiated mechanism's context.
+-		 */
+-		*context_handle = (gss_ctx_id_t)spnego_ctx->ctx_handle;
++		spnego_ctx->opened = 1;
+ 		if (actual_mech != NULL)
+ 			*actual_mech = spnego_ctx->actual_mech;
+ 		if (ret_flags != NULL)
+ 			*ret_flags = spnego_ctx->ctx_flags;
+-		release_spnego_ctx(&spnego_ctx);
+ 	} else if (ret != GSS_S_CONTINUE_NEEDED) {
+ 		if (spnego_ctx != NULL) {
+ 			gss_delete_sec_context(&tmpmin,
+@@ -1341,7 +1335,7 @@ acc_ctx_hints(OM_uint32 *minor_status,
+ 	if (ret != GSS_S_COMPLETE)
+ 		goto cleanup;
+ 
+-	sc = create_spnego_ctx();
++	sc = create_spnego_ctx(0);
+ 	if (sc == NULL) {
+ 		ret = GSS_S_FAILURE;
+ 		goto cleanup;
+@@ -1423,7 +1417,7 @@ acc_ctx_new(OM_uint32 *minor_status,
+ 		gss_release_buffer(&tmpmin, &sc->DER_mechTypes);
+ 		assert(mech_wanted != GSS_C_NO_OID);
+ 	} else
+-		sc = create_spnego_ctx();
++		sc = create_spnego_ctx(0);
+ 	if (sc == NULL) {
+ 		ret = GSS_S_FAILURE;
+ 		*return_token = NO_TOKEN_SEND;
+@@ -1806,13 +1800,12 @@ cleanup:
+ 			ret = GSS_S_FAILURE;
+ 	}
+ 	if (ret == GSS_S_COMPLETE) {
+-		*context_handle = (gss_ctx_id_t)sc->ctx_handle;
++		sc->opened = 1;
+ 		if (sc->internal_name != GSS_C_NO_NAME &&
+ 		    src_name != NULL) {
+ 			*src_name = sc->internal_name;
+ 			sc->internal_name = GSS_C_NO_NAME;
+ 		}
+-		release_spnego_ctx(&sc);
+ 	} else if (ret != GSS_S_CONTINUE_NEEDED) {
+ 		if (sc != NULL) {
+ 			gss_delete_sec_context(&tmpmin, &sc->ctx_handle,
+@@ -2125,8 +2118,13 @@ spnego_gss_unwrap(
+ 		gss_qop_t *qop_state)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_unwrap(minor_status,
+-			context_handle,
++			sc->ctx_handle,
+ 			input_message_buffer,
+ 			output_message_buffer,
+ 			conf_state,
+@@ -2146,8 +2144,13 @@ spnego_gss_wrap(
+ 		gss_buffer_t output_message_buffer)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_wrap(minor_status,
+-		    context_handle,
++		    sc->ctx_handle,
+ 		    conf_req_flag,
+ 		    qop_req,
+ 		    input_message_buffer,
+@@ -2164,8 +2167,14 @@ spnego_gss_process_context_token(
+ 				const gss_buffer_t token_buffer)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	/* SPNEGO doesn't have its own context tokens. */
++	if (!sc->opened)
++		return (GSS_S_DEFECTIVE_TOKEN);
++
+ 	ret = gss_process_context_token(minor_status,
+-					context_handle,
++					sc->ctx_handle,
+ 					token_buffer);
+ 
+ 	return (ret);
+@@ -2189,19 +2198,9 @@ spnego_gss_delete_sec_context(
+ 	if (*ctx == NULL)
+ 		return (GSS_S_COMPLETE);
+ 
+-	/*
+-	 * If this is still an SPNEGO mech, release it locally.
+-	 */
+-	if ((*ctx)->magic_num == SPNEGO_MAGIC_ID) {
+-		(void) gss_delete_sec_context(minor_status,
+-				    &(*ctx)->ctx_handle,
+-				    output_token);
+-		(void) release_spnego_ctx(ctx);
+-	} else {
+-		ret = gss_delete_sec_context(minor_status,
+-				    context_handle,
+-				    output_token);
+-	}
++	(void) gss_delete_sec_context(minor_status, &(*ctx)->ctx_handle,
++				      output_token);
++	(void) release_spnego_ctx(ctx);
+ 
+ 	return (ret);
+ }
+@@ -2213,8 +2212,13 @@ spnego_gss_context_time(
+ 			OM_uint32	*time_rec)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_context_time(minor_status,
+-			    context_handle,
++			    sc->ctx_handle,
+ 			    time_rec);
+ 	return (ret);
+ }
+@@ -2226,9 +2230,20 @@ spnego_gss_export_sec_context(
+ 			    gss_buffer_t interprocess_token)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = *(spnego_gss_ctx_id_t *)context_handle;
++
++	/* We don't currently support exporting partially established
++	 * contexts. */
++	if (!sc->opened)
++		return GSS_S_UNAVAILABLE;
++
+ 	ret = gss_export_sec_context(minor_status,
+-				    context_handle,
++				    &sc->ctx_handle,
+ 				    interprocess_token);
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT) {
++		release_spnego_ctx(&sc);
++		*context_handle = GSS_C_NO_CONTEXT;
++	}
+ 	return (ret);
+ }
+ 
+@@ -2238,11 +2253,12 @@ spnego_gss_import_sec_context(
+ 	const gss_buffer_t	interprocess_token,
+ 	gss_ctx_id_t		*context_handle)
+ {
+-	OM_uint32 ret;
+-	ret = gss_import_sec_context(minor_status,
+-				    interprocess_token,
+-				    context_handle);
+-	return (ret);
++	/*
++	 * Until we implement partial context exports, there are no SPNEGO
++	 * exported context tokens, only tokens for underlying mechs.  So just
++	 * return an error for now.
++	 */
++	return GSS_S_UNAVAILABLE;
+ }
+ #endif /* LEAN_CLIENT */
+ 
+@@ -2259,16 +2275,48 @@ spnego_gss_inquire_context(
+ 			int		*opened)
+ {
+ 	OM_uint32 ret = GSS_S_COMPLETE;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (src_name != NULL)
++		*src_name = GSS_C_NO_NAME;
++	if (targ_name != NULL)
++		*targ_name = GSS_C_NO_NAME;
++	if (lifetime_rec != NULL)
++		*lifetime_rec = 0;
++	if (mech_type != NULL)
++		*mech_type = (gss_OID)gss_mech_spnego;
++	if (ctx_flags != NULL)
++		*ctx_flags = 0;
++	if (locally_initiated != NULL)
++		*locally_initiated = sc->initiate;
++	if (opened != NULL)
++		*opened = sc->opened;
++
++	if (sc->ctx_handle != GSS_C_NO_CONTEXT) {
++		ret = gss_inquire_context(minor_status, sc->ctx_handle,
++					  src_name, targ_name, lifetime_rec,
++					  mech_type, ctx_flags, NULL, NULL);
++	}
+ 
+-	ret = gss_inquire_context(minor_status,
+-				context_handle,
+-				src_name,
+-				targ_name,
+-				lifetime_rec,
+-				mech_type,
+-				ctx_flags,
+-				locally_initiated,
+-				opened);
++	if (!sc->opened) {
++		/*
++		 * We are still doing SPNEGO negotiation, so report SPNEGO as
++		 * the OID.  After negotiation is complete we will report the
++		 * underlying mechanism OID.
++		 */
++		if (mech_type != NULL)
++			*mech_type = (gss_OID)gss_mech_spnego;
++
++		/*
++		 * Remove flags we don't support with partially-established
++		 * contexts.  (Change this to keep GSS_C_TRANS_FLAG if we add
++		 * support for exporting partial SPNEGO contexts.)
++		 */
++		if (ctx_flags != NULL) {
++			*ctx_flags &= ~GSS_C_PROT_READY_FLAG;
++			*ctx_flags &= ~GSS_C_TRANS_FLAG;
++		}
++	}
+ 
+ 	return (ret);
+ }
+@@ -2283,8 +2331,13 @@ spnego_gss_wrap_size_limit(
+ 	OM_uint32	*max_input_size)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_wrap_size_limit(minor_status,
+-				context_handle,
++				sc->ctx_handle,
+ 				conf_req_flag,
+ 				qop_req,
+ 				req_output_size,
+@@ -2301,8 +2354,13 @@ spnego_gss_get_mic(
+ 		gss_buffer_t message_token)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_get_mic(minor_status,
+-		    context_handle,
++		    sc->ctx_handle,
+ 		    qop_req,
+ 		    message_buffer,
+ 		    message_token);
+@@ -2318,8 +2376,13 @@ spnego_gss_verify_mic(
+ 		gss_qop_t *qop_state)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_verify_mic(minor_status,
+-			    context_handle,
++			    sc->ctx_handle,
+ 			    msg_buffer,
+ 			    token_buffer,
+ 			    qop_state);
+@@ -2334,8 +2397,14 @@ spnego_gss_inquire_sec_context_by_oid(
+ 		gss_buffer_set_t *data_set)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	/* There are no SPNEGO-specific OIDs for this function. */
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_UNAVAILABLE);
++
+ 	ret = gss_inquire_sec_context_by_oid(minor_status,
+-			    context_handle,
++			    sc->ctx_handle,
+ 			    desired_object,
+ 			    data_set);
+ 	return (ret);
+@@ -2404,8 +2473,15 @@ spnego_gss_set_sec_context_option(
+ 		const gss_buffer_t value)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)*context_handle;
++
++	/* There are no SPNEGO-specific OIDs for this function, and we cannot
++	 * construct an empty SPNEGO context with it. */
++	if (sc == NULL || sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_UNAVAILABLE);
++
+ 	ret = gss_set_sec_context_option(minor_status,
+-			    context_handle,
++			    &sc->ctx_handle,
+ 			    desired_object,
+ 			    value);
+ 	return (ret);
+@@ -2422,8 +2498,13 @@ spnego_gss_wrap_aead(OM_uint32 *minor_status,
+ 		     gss_buffer_t output_message_buffer)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_wrap_aead(minor_status,
+-			    context_handle,
++			    sc->ctx_handle,
+ 			    conf_req_flag,
+ 			    qop_req,
+ 			    input_assoc_buffer,
+@@ -2444,8 +2525,13 @@ spnego_gss_unwrap_aead(OM_uint32 *minor_status,
+ 		       gss_qop_t *qop_state)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_unwrap_aead(minor_status,
+-			      context_handle,
++			      sc->ctx_handle,
+ 			      input_message_buffer,
+ 			      input_assoc_buffer,
+ 			      output_payload_buffer,
+@@ -2464,8 +2550,13 @@ spnego_gss_wrap_iov(OM_uint32 *minor_status,
+ 		    int iov_count)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_wrap_iov(minor_status,
+-			   context_handle,
++			   sc->ctx_handle,
+ 			   conf_req_flag,
+ 			   qop_req,
+ 			   conf_state,
+@@ -2483,8 +2574,13 @@ spnego_gss_unwrap_iov(OM_uint32 *minor_status,
+ 		      int iov_count)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_unwrap_iov(minor_status,
+-			     context_handle,
++			     sc->ctx_handle,
+ 			     conf_state,
+ 			     qop_state,
+ 			     iov,
+@@ -2502,8 +2598,13 @@ spnego_gss_wrap_iov_length(OM_uint32 *minor_status,
+ 			   int iov_count)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_wrap_iov_length(minor_status,
+-				  context_handle,
++				  sc->ctx_handle,
+ 				  conf_req_flag,
+ 				  qop_req,
+ 				  conf_state,
+@@ -2520,8 +2621,13 @@ spnego_gss_complete_auth_token(
+ 		gss_buffer_t input_message_buffer)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_UNAVAILABLE);
++
+ 	ret = gss_complete_auth_token(minor_status,
+-				      context_handle,
++				      sc->ctx_handle,
+ 				      input_message_buffer);
+ 	return (ret);
+ }
+@@ -2773,8 +2879,13 @@ spnego_gss_pseudo_random(OM_uint32 *minor_status,
+ 			 gss_buffer_t prf_out)
+ {
+ 	OM_uint32 ret;
++	spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context;
++
++	if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++		return (GSS_S_NO_CONTEXT);
++
+ 	ret = gss_pseudo_random(minor_status,
+-				context,
++				sc->ctx_handle,
+ 				prf_key,
+ 				prf_in,
+ 				desired_output_len,
+@@ -2915,7 +3026,12 @@ spnego_gss_get_mic_iov(OM_uint32 *minor_status, gss_ctx_id_t context_handle,
+ 		       gss_qop_t qop_req, gss_iov_buffer_desc *iov,
+ 		       int iov_count)
+ {
+-    return gss_get_mic_iov(minor_status, context_handle, qop_req, iov,
++    spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++    if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++	    return (GSS_S_NO_CONTEXT);
++
++    return gss_get_mic_iov(minor_status, sc->ctx_handle, qop_req, iov,
+ 			   iov_count);
+ }
+ 
+@@ -2924,7 +3040,12 @@ spnego_gss_verify_mic_iov(OM_uint32 *minor_status, gss_ctx_id_t context_handle,
+ 			  gss_qop_t *qop_state, gss_iov_buffer_desc *iov,
+ 			  int iov_count)
+ {
+-    return gss_verify_mic_iov(minor_status, context_handle, qop_state, iov,
++    spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++    if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++	    return (GSS_S_NO_CONTEXT);
++
++    return gss_verify_mic_iov(minor_status, sc->ctx_handle, qop_state, iov,
+ 			      iov_count);
+ }
+ 
+@@ -2933,7 +3054,12 @@ spnego_gss_get_mic_iov_length(OM_uint32 *minor_status,
+ 			      gss_ctx_id_t context_handle, gss_qop_t qop_req,
+ 			      gss_iov_buffer_desc *iov, int iov_count)
+ {
+-    return gss_get_mic_iov_length(minor_status, context_handle, qop_req, iov,
++    spnego_gss_ctx_id_t sc = (spnego_gss_ctx_id_t)context_handle;
++
++    if (sc->ctx_handle == GSS_C_NO_CONTEXT)
++	    return (GSS_S_NO_CONTEXT);
++
++    return gss_get_mic_iov_length(minor_status, sc->ctx_handle, qop_req, iov,
+ 				  iov_count);
+ }
+ 
+-- 
+1.9.1
+
diff --git a/meta-oe/recipes-connectivity/krb5/krb5_1.13.2.bb b/meta-oe/recipes-connectivity/krb5/krb5_1.13.2.bb
index ec88296df6..1b02f1a04a 100644
--- a/meta-oe/recipes-connectivity/krb5/krb5_1.13.2.bb
+++ b/meta-oe/recipes-connectivity/krb5/krb5_1.13.2.bb
@@ -23,6 +23,7 @@ SHRT_VER = "${@oe.utils.trim_version("${PV}", 2)}"
 SRC_URI = "http://web.mit.edu/kerberos/dist/${BPN}/${SHRT_VER}/${BP}-signed.tar \
            file://0001-aclocal-Add-parameter-to-disable-keyutils-detection.patch \
            file://debian-suppress-usr-lib-in-krb5-config.patch;striplevel=2 \
+           file://Fix-SPNEGO-context-aliasing-bugs-CVE-2015-2695.patch;striplevel=2 \
            file://crosscompile_nm.patch \
            file://etc/init.d/krb5-kdc \
            file://etc/init.d/krb5-admin-server \