commit d05da1fa45f9b40cc5a56f7d9ff1c55992590168
author Jarno Lamsa <jarno.lamsa@arm.com> Thu Nov 14 10:12:36 2019 +0200
committer Jarno Lamsa <jarno.lamsa@arm.com> Thu Dec 19 07:56:10 2019 +0200
tree b6e760770c67f29feb7c484d731f97802c92edfb
parent 552e8f2d6a28bdd664f01da2564ea261dcf56477

Add double check for checking if source is strong

To prevent glitching past a strong source.

library/entropy.c

diff --git a/library/entropy.c b/library/entropy.c
index fdb2e15..6b0b47b 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -271,7 +271,13 @@
      */
     for( i = 0; i < ctx->source_count; i++ )
     {
-        if( ctx->source[i].strong == MBEDTLS_ENTROPY_SOURCE_STRONG )
+        volatile int strong_fi = ctx->source[i].strong;
+        if( strong_fi == MBEDTLS_ENTROPY_SOURCE_STRONG )
+            have_one_strong_fi = 1;
+
+        mbedtls_platform_enforce_volatile_reads();
+
+        if( strong_fi == MBEDTLS_ENTROPY_SOURCE_STRONG )
             have_one_strong_fi = 1;
 
         olen = 0;