commit 3d01f2313b289fcc5a607237b3999a61a0b0506c
author Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Tue Oct 22 09:54:55 2019 +0200
committer Manuel Pégourié-Gonnard <manuel.pegourie-gonnard@arm.com> Tue Oct 22 10:03:07 2019 +0200
tree 004fb7c4ce9bb1d5841eab76bcbf2ee8cb33cff7
parent 895454da016ffde7310080e51321ac982c4b76ea

Use plain memset() in HMAC-DRBG seeding

The line above the memset() relies on the fact that V is all-zero at that
point (see the comment above), so it doesn't contain a sensitive value.

library/hmac_drbg.c

diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index 03c7d67..b51e9b1 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -141,7 +141,7 @@
     if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V,
                                         mbedtls_md_get_size( md_info ) ) ) != 0 )
         return( ret );
-    mbedtls_platform_memset( ctx->V, 0x01, mbedtls_md_get_size( md_info ) );
+    memset( ctx->V, 0x01, mbedtls_md_get_size( md_info ) );
 
     if( ( ret = mbedtls_hmac_drbg_update_ret( ctx, data, data_len ) ) != 0 )
         return( ret );
@@ -268,7 +268,7 @@
      */
     if( ( ret = mbedtls_md_hmac_starts( &ctx->md_ctx, ctx->V, md_size ) ) != 0 )
         return( ret );
-    mbedtls_platform_memset( ctx->V, 0x01, md_size );
+    memset( ctx->V, 0x01, md_size );
 
     ctx->f_entropy = f_entropy;
     ctx->p_entropy = p_entropy;