From 1b9b217abffd67db8bba3d06c74cbbb94740060b Mon Sep 17 00:00:00 2001
From: Ron Eldor <Ron.Eldor@arm.com>
Date: Thu, 26 Apr 2018 14:15:01 +0300
Subject: [PATCH] enforce input and output of ccm selftest on stack

In `mbedtls_ccm_self_test()`, enforce input and output
buffers sent to the ccm API to be contigous and aligned,
by copying the test vectors to buffers on the stack.
---
 library/ccm.c | 36 ++++++++++++++++++++++++------------
 1 file changed, 24 insertions(+), 12 deletions(-)

diff --git a/library/ccm.c b/library/ccm.c
index 804eaf80f..90cab8e14 100644
--- a/library/ccm.c
+++ b/library/ccm.c
@@ -381,7 +381,8 @@ int mbedtls_ccm_auth_decrypt( mbedtls_ccm_context *ctx, size_t length,
  */
 
 #define NB_TESTS 3
-
+#define CCM_SELFTEST_PT_MAX_LEN 24
+#define CCM_SELFTEST_CT_MAX_LEN 32
 /*
  * The data is the same for all tests, only the used length changes
  */
@@ -401,7 +402,7 @@ static const unsigned char ad[] = {
     0x10, 0x11, 0x12, 0x13
 };
 
-static const unsigned char msg[] = {
+static const unsigned char msg[CCM_SELFTEST_PT_MAX_LEN] = {
     0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
     0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
     0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
@@ -412,7 +413,7 @@ static const size_t add_len[NB_TESTS] = { 8, 16, 20 };
 static const size_t msg_len[NB_TESTS] = { 4, 16, 24 };
 static const size_t tag_len[NB_TESTS] = { 4, 6,  8  };
 
-static const unsigned char res[NB_TESTS][32] = {
+static const unsigned char res[NB_TESTS][CCM_SELFTEST_CT_MAX_LEN] = {
     {   0x71, 0x62, 0x01, 0x5b, 0x4d, 0xac, 0x25, 0x5d },
     {   0xd2, 0xa1, 0xf0, 0xe0, 0x51, 0xea, 0x5f, 0x62,
         0x08, 0x1a, 0x77, 0x92, 0x07, 0x3d, 0x59, 0x3d,
@@ -426,7 +427,13 @@ static const unsigned char res[NB_TESTS][32] = {
 int mbedtls_ccm_self_test( int verbose )
 {
     mbedtls_ccm_context ctx;
-    unsigned char out[32];
+    /*
+     * Some hardware accelerators require the input and output buffers
+     * would be in RAM, because the flash is not accessible.
+     * Use buffers on the stack to hold the test vectors data.
+     */
+    unsigned char plaintext[CCM_SELFTEST_PT_MAX_LEN];
+    unsigned char ciphertext[CCM_SELFTEST_CT_MAX_LEN];
     size_t i;
     int ret;
 
@@ -445,27 +452,32 @@ int mbedtls_ccm_self_test( int verbose )
         if( verbose != 0 )
             mbedtls_printf( "  CCM-AES #%u: ", (unsigned int) i + 1 );
 
+        memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN );
+        memset( ciphertext, 0, CCM_SELFTEST_CT_MAX_LEN );
+        memcpy( plaintext, msg, msg_len[i] );
+
         ret = mbedtls_ccm_encrypt_and_tag( &ctx, msg_len[i],
-                                   iv, iv_len[i], ad, add_len[i],
-                                   msg, out,
-                                   out + msg_len[i], tag_len[i] );
+                                           iv, iv_len[i], ad, add_len[i],
+                                           plaintext, ciphertext,
+                                           ciphertext + msg_len[i], tag_len[i] );
 
         if( ret != 0 ||
-            memcmp( out, res[i], msg_len[i] + tag_len[i] ) != 0 )
+            memcmp( ciphertext, res[i], msg_len[i] + tag_len[i] ) != 0 )
         {
             if( verbose != 0 )
                 mbedtls_printf( "failed\n" );
 
             return( 1 );
         }
+        memset( plaintext, 0, CCM_SELFTEST_PT_MAX_LEN );
 
         ret = mbedtls_ccm_auth_decrypt( &ctx, msg_len[i],
-                                iv, iv_len[i], ad, add_len[i],
-                                res[i], out,
-                                res[i] + msg_len[i], tag_len[i] );
+                                        iv, iv_len[i], ad, add_len[i],
+                                        ciphertext, plaintext,
+                                        ciphertext + msg_len[i], tag_len[i] );
 
         if( ret != 0 ||
-            memcmp( out, msg, msg_len[i] ) != 0 )
+            memcmp( plaintext, msg, msg_len[i] ) != 0 )
         {
             if( verbose != 0 )
                 mbedtls_printf( "failed\n" );