Fix a nonce re-use bug:

https://w1.fi/security/2017-1/wpa-packet-number-reuse-with-replayed-messages.txt

Patch copied from upstream:

https://w1.fi/security/2017-1/rebased-v2.6-0005-Fix-PTK-rekeying-to-generate-a-new-ANonce.patch

From 12fac09b437a1dc8a0f253e265934a8aaf4d2f8b Mon Sep 17 00:00:00 2001
From: Jouni Malinen <j@w1.fi>
Date: Sun, 1 Oct 2017 12:32:57 +0300
Subject: [PATCH 5/8] Fix PTK rekeying to generate a new ANonce

The Authenticator state machine path for PTK rekeying ended up bypassing
the AUTHENTICATION2 state where a new ANonce is generated when going
directly to the PTKSTART state since there is no need to try to
determine the PMK again in such a case. This is far from ideal since the
new PTK would depend on a new nonce only from the supplicant.

Fix this by generating a new ANonce when moving to the PTKSTART state
for the purpose of starting new 4-way handshake to rekey PTK.

Signed-off-by: Jouni Malinen <j@w1.fi>
---
 src/ap/wpa_auth.c | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/src/ap/wpa_auth.c b/src/ap/wpa_auth.c
index 707971d..bf10cc1 100644
--- a/src/ap/wpa_auth.c
+++ b/src/ap/wpa_auth.c
@@ -1901,6 +1901,21 @@ SM_STATE(WPA_PTK, AUTHENTICATION2)
 }
 
 
+static int wpa_auth_sm_ptk_update(struct wpa_state_machine *sm)
+{
+	if (random_get_bytes(sm->ANonce, WPA_NONCE_LEN)) {
+		wpa_printf(MSG_ERROR,
+			   "WPA: Failed to get random data for ANonce");
+		sm->Disconnect = TRUE;
+		return -1;
+	}
+	wpa_hexdump(MSG_DEBUG, "WPA: Assign new ANonce", sm->ANonce,
+		    WPA_NONCE_LEN);
+	sm->TimeoutCtr = 0;
+	return 0;
+}
+
+
 SM_STATE(WPA_PTK, INITPMK)
 {
 	u8 msk[2 * PMK_LEN];
@@ -2458,9 +2473,12 @@ SM_STEP(WPA_PTK)
 		SM_ENTER(WPA_PTK, AUTHENTICATION);
 	else if (sm->ReAuthenticationRequest)
 		SM_ENTER(WPA_PTK, AUTHENTICATION2);
-	else if (sm->PTKRequest)
-		SM_ENTER(WPA_PTK, PTKSTART);
-	else switch (sm->wpa_ptk_state) {
+	else if (sm->PTKRequest) {
+		if (wpa_auth_sm_ptk_update(sm) < 0)
+			SM_ENTER(WPA_PTK, DISCONNECTED);
+		else
+			SM_ENTER(WPA_PTK, PTKSTART);
+	} else switch (sm->wpa_ptk_state) {
 	case WPA_PTK_INITIALIZE:
 		break;
 	case WPA_PTK_DISCONNECT:
-- 
2.7.4

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