Backport 2.1:Fix crash when calling `mbedtls_ssl_cache_free` twice
Set `cache` to zero at the end of `mbedtls_ssl_cache_free` #1104
diff --git a/ChangeLog b/ChangeLog
index da29d70..1df65ed 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -12,6 +12,8 @@
* Fix leap year calculation in x509_date_is_valid() to ensure that invalid
dates on leap years with 100 and 400 intervals are handled correctly. Found
by Nicholas Wilson. #694
+ * Fix crash when calling mbedtls_ssl_cache_free() twice. Found by
+ MilenkoMitrovic, #1104
= mbed TLS 2.1.9 branch released 2017-08-10
diff --git a/library/ssl_cache.c b/library/ssl_cache.c
index 711bc53..47107b6 100644
--- a/library/ssl_cache.c
+++ b/library/ssl_cache.c
@@ -43,6 +43,15 @@
#define mbedtls_free free
#endif
+#include "mbedtls/ssl_cache.h"
+
+#include <string.h>
+
+/* Implementation that should never be optimized out by the compiler */
+static void mbedtls_zeroize( void *v, size_t n ) {
+ volatile unsigned char *p = v; while( n-- ) *p++ = 0;
+}
+
void mbedtls_ssl_cache_init( mbedtls_ssl_cache_context *cache )
{
memset( cache, 0, sizeof( mbedtls_ssl_cache_context ) );
@@ -321,6 +330,8 @@
#if defined(MBEDTLS_THREADING_C)
mbedtls_mutex_free( &cache->mutex );
#endif
+
+ mbedtls_zeroize( cache, sizeof(mbedtls_ssl_cache_context) );
}
#endif /* MBEDTLS_SSL_CACHE_C */