From: Matthias-Christian Ott <ott@mirix.org>
Date: Tue, 30 Dec 2014 09:58:43 +0000 (+0200)
Subject: Don't call _gnutls_cipher_encrypt2 with textlen = 0 in _gnutls_auth_cipher_encrypt2_tag
X-Git-Tag: gnutls_3_4_0~422
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9a6f355f2619bf04a2d72c0eca0e8bc9d41cda28;p=thirdparty%2Fgnutls.git

Don't call _gnutls_cipher_encrypt2 with textlen = 0 in _gnutls_auth_cipher_encrypt2_tag

If the plaintext is shorter than the block size of the used cipher,
_gnutls_auth_cipher_encrypt2_tag calls _gnutls_cipher_encrypt2 with
textlen = 0. By definition _gnutls_cipher_encrypt2 does nothing in this
case and thus does not need to be called.
---

diff --git a/lib/gnutls_cipher_int.c b/lib/gnutls_cipher_int.c
index 31b608c46f..3368bae5b4 100644
--- a/lib/gnutls_cipher_int.c
+++ b/lib/gnutls_cipher_int.c
@@ -266,17 +266,19 @@ int _gnutls_auth_cipher_encrypt2_tag(auth_cipher_hd_st * handle,
 				return gnutls_assert_val(GNUTLS_E_INTERNAL_ERROR);
 
 			l = (textlen / blocksize) * blocksize;
-			ret =
-			    _gnutls_cipher_encrypt2(&handle->cipher, text,
+			if (l > 0) {
+				ret =
+			    	_gnutls_cipher_encrypt2(&handle->cipher, text,
 						    l, ciphertext,
 						    ciphertextlen);
-			if (ret < 0)
-				return gnutls_assert_val(ret);
+				if (ret < 0)
+					return gnutls_assert_val(ret);
 
-			textlen -= l;
-			text += l;
-			ciphertext += l;
-			ciphertextlen -= l;
+				textlen -= l;
+				text += l;
+				ciphertext += l;
+				ciphertextlen -= l;
+			}
 
 			if (ciphertext != text && textlen > 0)
 				memcpy(ciphertext, text, textlen);