From 3d979f781e7d49810b6a72f41a18c7347b624361 Mon Sep 17 00:00:00 2001
From: Gilles Peskine <Gilles.Peskine@arm.com>
Date: Mon, 22 Feb 2021 21:24:02 +0100
Subject: [PATCH] Add init-free tests for entropy

These tests validate that an entropy object can be reused and that
calling mbedtls_entropy_free() twice is ok.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
---
 tests/suites/test_suite_entropy.data     |  6 ++++++
 tests/suites/test_suite_entropy.function | 22 ++++++++++++++++++++++
 2 files changed, 28 insertions(+)

diff --git a/tests/suites/test_suite_entropy.data b/tests/suites/test_suite_entropy.data
index b2d20b472..2ce01fabd 100644
--- a/tests/suites/test_suite_entropy.data
+++ b/tests/suites/test_suite_entropy.data
@@ -1,3 +1,9 @@
+Entropy init-free-free
+entropy_init_free:0
+
+Entropy init-free-init-free
+entropy_init_free:1
+
 Create NV seed_file
 nv_seed_file_create:
 
diff --git a/tests/suites/test_suite_entropy.function b/tests/suites/test_suite_entropy.function
index 2a7b0de13..ad9b5a45a 100644
--- a/tests/suites/test_suite_entropy.function
+++ b/tests/suites/test_suite_entropy.function
@@ -134,6 +134,28 @@ int read_nv_seed( unsigned char *buf, size_t buf_len )
  * END_DEPENDENCIES
  */
 
+/* BEGIN_CASE */
+void entropy_init_free( int reinit )
+{
+    mbedtls_entropy_context ctx;
+
+    /* Double free is not explicitly documented to work, but it is convenient
+     * to call mbedtls_entropy_free() unconditionally on an error path without
+     * checking whether it has already been called in the success path. */
+
+    mbedtls_entropy_init( &ctx );
+    mbedtls_entropy_free( &ctx );
+
+    if( reinit )
+        mbedtls_entropy_init( &ctx );
+    mbedtls_entropy_free( &ctx );
+
+    /* This test case always succeeds, functionally speaking. A plausible
+     * bug might trigger an invalid pointer dereference or a memory leak. */
+    goto exit;
+}
+/* END_CASE */
+
 /* BEGIN_CASE depends_on:MBEDTLS_ENTROPY_NV_SEED:MBEDTLS_FS_IO */
 void entropy_seed_file( char * path, int ret )
 {