commit 6e2cf25639285b6b913df6314ea89f2695876acc
author Gilles Peskine <Gilles.Peskine@arm.com> Tue Feb 09 18:44:02 2021 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Fri Feb 12 15:57:03 2021 +0100
tree c45bf05c9a4111b5085a947847d58db589a3e9a4
parent 085b69f8fd2493d665fcc32d874cb63516cf878d

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 64b536a..e275f1a 100644
--- a/library/ctr_drbg.c
+++ b/library/ctr_drbg.c
@@ -99,6 +99,7 @@
         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
@@ -376,6 +377,7 @@
 
     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