From a78c0632edd4c9c257362045dbf7c8ca4a045052 Mon Sep 17 00:00:00 2001
From: "Dr. Stephen Henson" <steve@openssl.org>
Date: Mon, 6 Jun 2005 22:39:43 +0000
Subject: [PATCH] Fix for padding X9.31 padding check and zero padding bytes.

---
 crypto/rsa/rsa_x931.c | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/crypto/rsa/rsa_x931.c b/crypto/rsa/rsa_x931.c
index 7d77213d13..e918654176 100644
--- a/crypto/rsa/rsa_x931.c
+++ b/crypto/rsa/rsa_x931.c
@@ -115,9 +115,9 @@ int RSA_padding_check_X931(unsigned char *to, int tlen,
 		return -1;
 		}
 
-	j=flen-3;
 	if (*p++ == 0x6B)
 		{
+		j=flen-3;
 		for (i = 0; i < j; i++)
 			{
 			unsigned char c = *p++;
@@ -130,15 +130,17 @@ int RSA_padding_check_X931(unsigned char *to, int tlen,
 				return -1;
 				}
 			}
-		}
 
-	j -= i;
+		j -= i;
+
+		if (i == 0)
+			{
+			RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_PADDING);
+			return -1;
+			}
 
-	if (i == 0)
-		{
-		RSAerr(RSA_F_RSA_PADDING_CHECK_X931, RSA_R_INVALID_PADDING);
-		return -1;
 		}
+	else j = flen - 2;
 
 	if (p[j] != 0xCC)
 		{
-- 
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