commit 2ecc0b89f3cfdeaee7416c1df58c585c7788170a
author Gilles Peskine <Gilles.Peskine@arm.com> Tue Feb 09 18:44:02 2021 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Mon Feb 22 19:40:41 2021 +0100
tree 71a8adb615da8b4fe64645429d4ea87a523f3315
parent 89816bc020b91cb6dd5c6df192ea16ebd8975903

Document mutex invariant for CTR_DRBG

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>

library/ctr_drbg.c

diff --git a/library/ctr_drbg.c b/library/ctr_drbg.c
index 5461b71..90264e8 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -95,6 +95,7 @@
         return;
 
 #if defined(MBEDTLS_THREADING_C)
+    /* The mutex is initialized iff f_entropy is set. */
     if( ctx->f_entropy != NULL )
         mbedtls_mutex_free( &ctx->mutex );
 #endif
@@ -416,6 +417,7 @@
 
     memset( key, 0, MBEDTLS_CTR_DRBG_KEYSIZE );
 
+    /* The mutex is initialized iff f_entropy is set. */
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_init( &ctx->mutex );
 #endif