From 4159f311671cf3bac03815e5de44681eb758304a Mon Sep 17 00:00:00 2001
From: Kurt Roeckx <kurt@roeckx.be>
Date: Sat, 16 Apr 2016 23:08:56 +0200
Subject: [PATCH] Check that we have enough padding characters.
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Reviewed-by: Emilia Käsper <emilia@openssl.org>

CVE-2016-2107

MR: #2572
---
 crypto/evp/e_aes_cbc_hmac_sha1.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/crypto/evp/e_aes_cbc_hmac_sha1.c b/crypto/evp/e_aes_cbc_hmac_sha1.c
index d1f5928f62..1d598db359 100644
--- a/crypto/evp/e_aes_cbc_hmac_sha1.c
+++ b/crypto/evp/e_aes_cbc_hmac_sha1.c
@@ -59,6 +59,7 @@
 # include <openssl/aes.h>
 # include <openssl/sha.h>
 # include "evp_locl.h"
+# include "constant_time_locl.h"
 
 # ifndef EVP_CIPH_FLAG_AEAD_CIPHER
 #  define EVP_CIPH_FLAG_AEAD_CIPHER       0x200000
@@ -286,6 +287,8 @@ static int aesni_cbc_hmac_sha1_cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
             maxpad |= (255 - maxpad) >> (sizeof(maxpad) * 8 - 8);
             maxpad &= 255;
 
+            ret &= constant_time_ge(maxpad, pad);
+
             inp_len = len - (SHA_DIGEST_LENGTH + pad + 1);
             mask = (0 - ((inp_len - len) >> (sizeof(inp_len) * 8 - 1)));
             inp_len &= mask;
-- 
2.25.1