commit 7d52f2a0d939c610e18f7cd2b7d3a6361f3d4a98
author Dave Rodgman <dave.rodgman@arm.com> Tue Sep 12 16:29:39 2023 +0100
committer Dave Rodgman <dave.rodgman@arm.com> Wed Sep 13 09:30:03 2023 +0100
tree 35f8647dee325d124717009d759cc4e7f3064658
parent 31beb2d449f2b6e01e28f2d063e99c9a27965312

Improve use of ct interface in mbedtls_ssl_decrypt_buf

Signed-off-by: Dave Rodgman <dave.rodgman@arm.com>

library/ssl_msg.c

diff --git a/library/ssl_msg.c b/library/ssl_msg.c
index 85632a1..47a206d 100644
--- a/library/ssl_msg.c
+++ b/library/ssl_msg.c
@@ -1504,7 +1504,8 @@
 
     int auth_done = 0;
 #if defined(MBEDTLS_SSL_SOME_SUITES_USE_MAC)
-    size_t padlen = 0, correct = 1;
+    size_t padlen = 0;
+    mbedtls_ct_condition_t correct = MBEDTLS_CT_TRUE;
 #endif
     unsigned char *data;
     /* For an explanation of the additional data length see
@@ -1921,7 +1922,7 @@
             const mbedtls_ct_condition_t ge = mbedtls_ct_uint_ge(
                 rec->data_len,
                 padlen + 1);
-            correct = mbedtls_ct_size_if_else_0(ge, correct);
+            correct = mbedtls_ct_bool_and(ge, correct);
             padlen  = mbedtls_ct_size_if_else_0(ge, padlen);
         } else {
 #if defined(MBEDTLS_SSL_DEBUG_ALL)
@@ -1937,7 +1938,7 @@
             const mbedtls_ct_condition_t ge = mbedtls_ct_uint_ge(
                 rec->data_len,
                 transform->maclen + padlen + 1);
-            correct = mbedtls_ct_size_if_else_0(ge, correct);
+            correct = mbedtls_ct_bool_and(ge, correct);
             padlen  = mbedtls_ct_size_if_else_0(ge, padlen);
         }
 
@@ -1973,14 +1974,14 @@
             increment = mbedtls_ct_size_if_else_0(b, increment);
             pad_count += increment;
         }
-        correct = mbedtls_ct_size_if_else_0(mbedtls_ct_uint_eq(pad_count, padlen), correct);
+        correct = mbedtls_ct_bool_and(mbedtls_ct_uint_eq(pad_count, padlen), correct);
 
 #if defined(MBEDTLS_SSL_DEBUG_ALL)
-        if (padlen > 0 && correct == 0) {
+        if (padlen > 0 && correct == MBEDTLS_CT_FALSE) {
             MBEDTLS_SSL_DEBUG_MSG(1, ("bad padding byte detected"));
         }
 #endif
-        padlen = mbedtls_ct_size_if_else_0(mbedtls_ct_bool(correct), padlen);
+        padlen = mbedtls_ct_size_if_else_0(correct, padlen);
 
 #endif /* MBEDTLS_SSL_PROTO_TLS1_2 */
 
@@ -2075,7 +2076,7 @@
 #if defined(MBEDTLS_SSL_DEBUG_ALL)
             MBEDTLS_SSL_DEBUG_MSG(1, ("message mac does not match"));
 #endif
-            correct = 0;
+            correct = MBEDTLS_CT_FALSE;
         }
         auth_done++;
 
@@ -2090,7 +2091,7 @@
     /*
      * Finally check the correct flag
      */
-    if (correct == 0) {
+    if (correct == MBEDTLS_CT_FALSE) {
         return MBEDTLS_ERR_SSL_INVALID_MAC;
     }
 #endif /* MBEDTLS_SSL_SOME_SUITES_USE_MAC */