- fix paddding in TLS1.1 and DTLS on amd64

1 files changed, 72 insertions, 0 deletions

diff --git a/security/openssl/files/patch-tls-bug b/security/openssl/files/patch-tls-bug
new file mode 100644
index 000000000000..d3fb14357b65
--- /dev/null
+++ b/security/openssl/files/patch-tls-bug
@@ -0,0 +1,72 @@
+From 32cc2479b473c49ce869e57fded7e9a77b695c0d Mon Sep 17 00:00:00 2001
+From: "Dr. Stephen Henson" <steve@openssl.org>
+Date: Thu, 7 Feb 2013 21:06:37 +0000
+Subject: [PATCH] Fix IV check and padding removal.
+
+Fix the calculation that checks there is enough room in a record
+after removing padding and optional explicit IV. (by Steve)
+
+For AEAD remove the correct number of padding bytes (by Andy)
+---
+ ssl/s3_cbc.c |   33 ++++++++++++---------------------
+ 1 file changed, 12 insertions(+), 21 deletions(-)
+
+diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c
+index ce77acd..0f60507 100644
+--- a/ssl/s3_cbc.c
++++ ssl/s3_cbc.c
+@@ -139,31 +139,22 @@ int tls1_cbc_remove_padding(const SSL* s,
+ 			    unsigned mac_size)
+ 	{
+ 	unsigned padding_length, good, to_check, i;
+-	const char has_explicit_iv =
+-		s->version >= TLS1_1_VERSION || s->version == DTLS1_VERSION;
+-	const unsigned overhead = 1 /* padding length byte */ +
+-				  mac_size +
+-				  (has_explicit_iv ? block_size : 0);
+-
+-	/* These lengths are all public so we can test them in non-constant
+-	 * time. */
+-	if (overhead > rec->length)
+-		return 0;
+-
+-	/* We can always safely skip the explicit IV. We check at the beginning
+-	 * of this function that the record has at least enough space for the
+-	 * IV, MAC and padding length byte. (These can be checked in
+-	 * non-constant time because it's all public information.) So, if the
+-	 * padding was invalid, then we didn't change |rec->length| and this is
+-	 * safe. If the padding was valid then we know that we have at least
+-	 * overhead+padding_length bytes of space and so this is still safe
+-	 * because overhead accounts for the explicit IV. */
+-	if (has_explicit_iv)
++	const unsigned overhead = 1 /* padding length byte */ + mac_size;
++	/* Check if version requires explicit IV */
++	if (s->version >= TLS1_1_VERSION || s->version == DTLS1_VERSION)
+ 		{
++		/* These lengths are all public so we can test them in
++		 * non-constant time.
++		 */
++		if (overhead + block_size > rec->length)
++			return 0;
++		/* We can now safely skip explicit IV */
+ 		rec->data += block_size;
+ 		rec->input += block_size;
+ 		rec->length -= block_size;
+ 		}
++	else if (overhead > rec->length)
++		return 0;
+ 
+ 	padding_length = rec->data[rec->length-1];
+ 
+@@ -190,7 +181,7 @@ int tls1_cbc_remove_padding(const SSL* s,
+ 	if (EVP_CIPHER_flags(s->enc_read_ctx->cipher)&EVP_CIPH_FLAG_AEAD_CIPHER)
+ 		{
+ 		/* padding is already verified */
+-		rec->length -= padding_length;
++		rec->length -= padding_length + 1;
+ 		return 1;
+ 		}
+ 
+-- 
+1.7.9.5
+