File gnutls-CVE-2020-13777.patch of Package gnutls.18749

From c2646aeee94e71cb15c90a3147cf3b5b0ca158ca Mon Sep 17 00:00:00 2001
From: Daiki Ueno <ueno@gnu.org>
Date: Tue, 2 Jun 2020 20:53:11 +0200
Subject: [PATCH 1/2] stek: differentiate initial state from valid time window
 of TOTP

There was a confusion in the TOTP implementation in stek.c.  When the
mechanism is initialized at the first time, it records the timestamp
but doesn't initialize the key.  This removes the timestamp recording
at the initialization phase, so the key is properly set later.

Signed-off-by: Daiki Ueno <ueno@gnu.org>
---
 lib/stek.c                        | 17 +++++------------
 tests/resume-with-previous-stek.c |  4 ++--
 3 files changed, 11 insertions(+), 18 deletions(-)

diff --git a/lib/stek.c b/lib/stek.c
index 2f885cee37..5ab9e7d2d1 100644
--- a/lib/stek.c
+++ b/lib/stek.c
@@ -323,20 +323,13 @@ int _gnutls_initialize_session_ticket_key_rotation(gnutls_session_t session, con
 	if (unlikely(session == NULL || key == NULL))
 		return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
 
-	if (session->key.totp.last_result == 0) {
-		int64_t t;
-		memcpy(session->key.initial_stek, key->data, key->size);
-		t = totp_next(session);
-		if (t < 0)
-			return gnutls_assert_val(t);
+	if (unlikely(session->key.totp.last_result != 0))
+		return GNUTLS_E_INVALID_REQUEST;
 
-		session->key.totp.last_result = t;
-		session->key.totp.was_rotated = 0;
-
-		return GNUTLS_E_SUCCESS;
-	}
+	memcpy(session->key.initial_stek, key->data, key->size);
 
-	return GNUTLS_E_INVALID_REQUEST;
+	session->key.totp.was_rotated = 0;
+	return 0;
 }
 
 /*
diff --git a/tests/resume-with-previous-stek.c b/tests/resume-with-previous-stek.c
index f212b188b9..05c1c90868 100644
--- a/tests/resume-with-previous-stek.c
+++ b/tests/resume-with-previous-stek.c
@@ -196,8 +196,8 @@ static void server(int fd, unsigned rounds, const char *prio)
 		serverx509cred = NULL;
 	}
 
-	if (num_stek_rotations != 2)
-		fail("STEK should be rotated exactly twice (%d)!\n", num_stek_rotations);
+	if (num_stek_rotations != 3)
+		fail("STEK should be rotated exactly three times (%d)!\n", num_stek_rotations);
 
 	if (serverx509cred)
 		gnutls_certificate_free_credentials(serverx509cred);
 
-- 
2.25.0
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