commit 96ae73b0ea49b550edb48cb97f2983213e071ecc
author Chris Jones <christopher.jones@arm.com> Fri Jan 08 17:04:59 2021 +0000
committer Chris Jones <christopher.jones@arm.com> Tue Apr 13 15:12:02 2021 +0100
tree 7439fa6aac6d747f6246b7c3c6a44f89f48e1b76
parent 528b0a6b18eefacaed7a447b2226cb15723de1ba

Add macro for error code addition

Adds a macro (`MBEDTLS_ERR_ADD`) to add error codes together and check that the
result will not be corrupted. This additional check is only enabled during
testing when `MBEDTLS_TEST_HOOKS` is defined.

Also includes a reference usage example in `rsa.c` where two high-level error
codes could be incorrectly added together under the right conditions. This now
ensures that when this error occurs during testing it will be correctly
reported.

Signed-off-by: Chris Jones <christopher.jones@arm.com>

library/error.c

diff --git a/library/error.c b/library/error.c
index 901a369..486afed 100644
--- a/library/error.c
+++ b/library/error.c
@@ -210,6 +210,13 @@
 #include "mbedtls/xtea.h"
 #endif
 
+#if defined(MBEDTLS_TEST_HOOKS)
+int mbedtls_err_add( int high, int low, const char *file, int line ) {
+    if( mbedtls_test_err_add_hook != NULL )
+        (*mbedtls_test_err_add_hook)( high, low, file, line );
+    return ( high + low );
+}
+#endif
 
 const char * mbedtls_high_level_strerr( int error_code )
 {

library/rsa.c

diff --git a/library/rsa.c b/library/rsa.c
index fea76bf..f4bec46 100644
--- a/library/rsa.c
+++ b/library/rsa.c
@@ -1085,7 +1085,7 @@
     mbedtls_mpi_free( &I );
 
     if( ret != 0 && ret >= -0x007f )
-        return( MBEDTLS_ERR_RSA_PRIVATE_FAILED + ret );
+        return( MBEDTLS_ERR_ADD( MBEDTLS_ERR_RSA_PRIVATE_FAILED, ret ) );
 
     return( ret );
 }