From d0890211287d80b06f8851bfc3c80498fb4ed2f5 Mon Sep 17 00:00:00 2001
From: Gilles Peskine <Gilles.Peskine@arm.com>
Date: Mon, 24 Jun 2019 14:34:43 +0200
Subject: [PATCH] Unregister drivers on library deinitialization

---
 library/psa_crypto.c    | 4 ++++
 library/psa_crypto_se.c | 7 +++++++
 library/psa_crypto_se.h | 8 ++++++++
 3 files changed, 19 insertions(+)

diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index b3be2617b..7e2007129 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -32,6 +32,7 @@
 
 #include "psa_crypto_core.h"
 #include "psa_crypto_invasive.h"
+#include "psa_crypto_se.h"
 #include "psa_crypto_slot_management.h"
 /* Include internal declarations that are useful for implementing persistently
  * stored keys. */
@@ -5211,6 +5212,9 @@ void mbedtls_psa_crypto_free( void )
      * In particular, this sets all state indicator to the value
      * indicating "uninitialized". */
     mbedtls_platform_zeroize( &global_data, sizeof( global_data ) );
+    /* Unregister all secure element drivers, so that we restart from
+     * a pristine state. */
+    psa_unregister_all_se_drivers( );
 }
 
 psa_status_t psa_crypto_init( void )
diff --git a/library/psa_crypto_se.c b/library/psa_crypto_se.c
index 33d0da894..32142eb9a 100644
--- a/library/psa_crypto_se.c
+++ b/library/psa_crypto_se.c
@@ -27,6 +27,8 @@
 
 #if defined(MBEDTLS_PSA_CRYPTO_C)
 
+#include <string.h>
+
 #include "psa_crypto_se.h"
 
 typedef struct
@@ -69,4 +71,9 @@ psa_status_t psa_register_se_driver(
     return( PSA_SUCCESS );
 }
 
+void psa_unregister_all_se_drivers( void )
+{
+    memset( driver_table, 0, sizeof( driver_table ) );
+}
+
 #endif /* MBEDTLS_PSA_CRYPTO_C */
diff --git a/library/psa_crypto_se.h b/library/psa_crypto_se.h
index 1085f488d..e99bd2576 100644
--- a/library/psa_crypto_se.h
+++ b/library/psa_crypto_se.h
@@ -34,4 +34,12 @@
 /** The maximum number of registered secure element driver lifetimes. */
 #define PSA_MAX_SE_DRIVERS 4
 
+/** Unregister all secure element drivers.
+ *
+ * \warning Do not call this function while the library is in the initialized
+ *          state. This function is only intended to be called at the end
+ *          of mbedtls_psa_crypto_free().
+ */
+void psa_unregister_all_se_drivers( void );
+
 #endif /* PSA_CRYPTO_SE_H */