commit 3ec7f57482d8336109960e92b334f2ad523106da
author Gilles Peskine <Gilles.Peskine@arm.com> Tue Feb 09 18:43:33 2021 +0100
committer Gilles Peskine <Gilles.Peskine@arm.com> Fri Feb 12 15:57:03 2021 +0100
tree 4b7c664684316afd907d2a877a77ba934b7f3823
parent a9857af16ab974b121689623dfbab9a6ab4d3608

Document mutex invariant for HMAC_DRBG

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

library/hmac_drbg.c

diff --git a/library/hmac_drbg.c b/library/hmac_drbg.c
index 8bd8a05..876fa57 100644
--- a/library/hmac_drbg.c
+++ b/library/hmac_drbg.c
@@ -286,6 +286,7 @@
     if( ( ret = mbedtls_md_setup( &ctx->md_ctx, md_info, 1 ) ) != 0 )
         return( ret );
 
+    /* The mutex is initialized iff the md context is set up. */
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_init( &ctx->mutex );
 #endif
@@ -457,6 +458,7 @@
         return;
 
 #if defined(MBEDTLS_THREADING_C)
+    /* The mutex is initialized iff the md context is set up. */
     if( ctx->md_ctx.md_info != NULL )
         mbedtls_mutex_free( &ctx->mutex );
 #endif