commit 436d18dcaa1d34d9508be7242d4e0ca7398bbfe0
author Jarno Lamsa <jarno.lamsa@arm.com> Thu Oct 03 11:46:30 2019 +0300
committer Jarno Lamsa <jarno.lamsa@arm.com> Thu Oct 03 13:49:35 2019 +0300
tree 86a0b624833e0739089642fc9bc8812fc9025e5d
parent e29e8a49b84f4dc8c15c51107fa87f5241344350

Prevent a 0-modulus

If given range for a random is [0, 0), return 0.
Modulus 0 is undefined behaviour.

library/platform_util.c

diff --git a/library/platform_util.c b/library/platform_util.c
index 6ba4112..9461a9c 100644
--- a/library/platform_util.c
+++ b/library/platform_util.c
@@ -150,7 +150,17 @@
 
     mbedtls_hardware_poll( NULL, (unsigned char *) &result, sizeof( result ),
                            &olen );
-    return( result % num );
+
+    if( num == 0 )
+    {
+        result = 0;
+    }
+    else
+    {
+        result %= num;
+    }
+
+    return( result );
 #endif
 }