[PATCH] mbedtls: remove MBEDTLS_HAVE_TIME

[Ilias Apalodimas]

When MbedTLS TLS features were added MBEDTLS_HAVE_TIME was defined as part
of enabling https:// support. However that pointed to the wrong function
which could crash if it received a NULL pointer.

Looking closer that function is not really needed, as it only seems to
increase the RNG entropy by using 4b of the current time and date. 
The reason that was enabled is that lwIP was unconditionally requiring it,
although it's configurable and can be turned off.

Since lwIP doesn't use that field anywhere else, make it conditional and
disable it from our config.

Fixes: commit a564f5094f62 ("mbedtls: Enable TLS 1.2 support")
Reported-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>
Signed-off-by: Ilias Apalodimas <ilias.apalodimas at linaro.org>
---
 lib/lwip/lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c | 2 ++
 lib/mbedtls/mbedtls_def_config.h                     | 3 ---
 2 files changed, 2 insertions(+), 3 deletions(-)

diff --git a/lib/lwip/lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c b/lib/lwip/lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c
index 6643b05ee94d..46421588fef8 100644
--- a/lib/lwip/lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c
+++ b/lib/lwip/lwip/src/apps/altcp_tls/altcp_tls_mbedtls.c
@@ -692,7 +692,9 @@ altcp_tls_set_session(struct altcp_pcb *conn, struct altcp_tls_session *session)
   if (session && conn && conn->state) {
     altcp_mbedtls_state_t *state = (altcp_mbedtls_state_t *)conn->state;
     int ret = -1;
+#ifdef MBEDTLS_HAVE_TIME
     if (session->data.MBEDTLS_PRIVATE(start))
+#endif
       ret = mbedtls_ssl_set_session(&state->ssl_context, &session->data);
     return ret < 0 ? ERR_VAL : ERR_OK;
   }
diff --git a/lib/mbedtls/mbedtls_def_config.h b/lib/mbedtls/mbedtls_def_config.h
index d27f017d0847..1d2314e90e4d 100644
--- a/lib/mbedtls/mbedtls_def_config.h
+++ b/lib/mbedtls/mbedtls_def_config.h
@@ -92,9 +92,6 @@
 
 /* Generic options */
 #define MBEDTLS_ENTROPY_HARDWARE_ALT
-#define MBEDTLS_HAVE_TIME
-#define MBEDTLS_PLATFORM_MS_TIME_ALT
-#define MBEDTLS_PLATFORM_TIME_MACRO rtc_mktime
 #define MBEDTLS_PLATFORM_C
 #define MBEDTLS_SSL_CLI_C
 #define MBEDTLS_SSL_TLS_C
-- 
2.45.2