diff --git a/include/mbedtls/config.h b/include/mbedtls/config.h
index 9751d26..f8684ac 100644
--- a/include/mbedtls/config.h
+++ b/include/mbedtls/config.h
@@ -256,6 +256,48 @@
  */
 //#define MBEDTLS_DEPRECATED_REMOVED
 
+/**
+ * \def MBEDTLS_CHECK_PARAMS
+ *
+ * This configuration option controls whether the library validates more of
+ * the parameters passed to it.
+ *
+ * When this flag is not defined, the library only attempts to validate an
+ * input parameter if: (1) they may come from the outside world (such as the
+ * network, the filesystem, etc.) or (2) not validating them could result in
+ * internal memory errors such as overflowing a buffer controlled by the
+ * library. On the other hand, it doesn't attempt to validate parameters whose
+ * values are fully controlled by the application (such as pointers).
+ *
+ * When this flag is defined, the library additionally attempts to validate
+ * parameters that are fully controlled by the application, and should always
+ * be valid if the application code is fully correct and trusted.
+ *
+ * For example, when a function accepts as input a pointer to a buffer that may
+ * contain untrusted data, and its documentation mentions that this pointer
+ * must not be NULL:
+ * - the pointer is checked to be non-NULL only if this option is enabled
+ * - the content of the buffer is always validated
+ *
+ * When this flag is defined, if a library function receives a parameter that
+ * is invalid, it will:
+ * - invoke the macro MBEDTLS_PARAM_FAILED() which by default expands to a
+ *   call to the function mbedtls_param_failed()
+ * - immediately return (with a specific error code unless the function
+ *   returns void and can't communicate an error).
+ *
+ * When defining this flag, you also need to:
+ * - either provide a definition of the function mbedtls_param_failed() in
+ *   your application (see platform_util.h for its prototype) as the library
+ *   calls that function, but does not provide a default definition for it,
+ * - or provide a different definition of the macro MBEDTLS_PARAM_FAILED()
+ *   below if the above mechanism is not flexible enough to suit your needs.
+ *   See the documentation of this macro later in this file.
+ *
+ * Uncomment to enable validation of application-controlled parameters.
+ */
+//#define MBEDTLS_CHECK_PARAMS
+
 /* \} name SECTION: System support */
 
 /**
@@ -414,11 +456,11 @@
  *      unsigned char mbedtls_internal_ecp_grp_capable(
  *          const mbedtls_ecp_group *grp )
  *      int  mbedtls_internal_ecp_init( const mbedtls_ecp_group *grp )
- *      void mbedtls_internal_ecp_deinit( const mbedtls_ecp_group *grp )
+ *      void mbedtls_internal_ecp_free( const mbedtls_ecp_group *grp )
  * The mbedtls_internal_ecp_grp_capable function should return 1 if the
  * replacement functions implement arithmetic for the given group and 0
  * otherwise.
- * The functions mbedtls_internal_ecp_init and mbedtls_internal_ecp_deinit are
+ * The functions mbedtls_internal_ecp_init and mbedtls_internal_ecp_free are
  * called before and after each point operation and provide an opportunity to
  * implement optimized set up and tear down instructions.
  *
@@ -3033,6 +3075,36 @@
 //#define MBEDTLS_PLATFORM_NV_SEED_READ_MACRO   mbedtls_platform_std_nv_seed_read /**< Default nv_seed_read function to use, can be undefined */
 //#define MBEDTLS_PLATFORM_NV_SEED_WRITE_MACRO  mbedtls_platform_std_nv_seed_write /**< Default nv_seed_write function to use, can be undefined */
 
+/**
+ * \brief       This macro is invoked by the library when an invalid parameter
+ *              is detected that is only checked with MBEDTLS_CHECK_PARAMS
+ *              (see the documentation of that option for context).
+ *
+ *              When you leave this undefined here, a default definition is
+ *              provided that invokes the function mbedtls_param_failed(),
+ *              which is declared in platform_util.h for the benefit of the
+ *              library, but that you need to define in your application.
+ *
+ *              When you define this here, this replaces the default
+ *              definition in platform_util.h (which no longer declares the
+ *              function mbedtls_param_failed()) and it is your responsibility
+ *              to make sure this macro expands to something suitable (in
+ *              particular, that all the necessary declarations are visible
+ *              from within the library - you can ensure that by providing
+ *              them in this file next to the macro definition).
+ *
+ *              Note that you may define this macro to expand to nothing, in
+ *              which case you don't have to worry about declarations or
+ *              definitions. However, you will then be notified about invalid
+ *              parameters only in non-void functions, and void function will
+ *              just silently return early on invalid parameters, which
+ *              partially negates the benefits of enabling
+ *              #MBEDTLS_CHECK_PARAMS in the first place, so is discouraged.
+ *
+ * \param cond  The expression that should evaluate to true, but doesn't.
+ */
+//#define MBEDTLS_PARAM_FAILED( cond )               assert( cond )
+
 /* SSL Cache options */
 //#define MBEDTLS_SSL_CACHE_DEFAULT_TIMEOUT       86400 /**< 1 day  */
 //#define MBEDTLS_SSL_CACHE_DEFAULT_MAX_ENTRIES      50 /**< Maximum entries in cache */
@@ -3041,31 +3113,65 @@
 
 /** \def MBEDTLS_SSL_MAX_CONTENT_LEN
  *
- * Maximum fragment length in bytes.
+ * Maximum length (in bytes) of incoming and outgoing plaintext fragments.
  *
- * Determines the size of both the incoming and outgoing TLS I/O buffers.
+ * This determines the size of both the incoming and outgoing TLS I/O buffers
+ * in such a way that both are capable of holding the specified amount of
+ * plaintext data, regardless of the protection mechanism used.
  *
- * Uncommenting MBEDTLS_SSL_IN_CONTENT_LEN and/or MBEDTLS_SSL_OUT_CONTENT_LEN
- * will override this length by setting maximum incoming and/or outgoing
- * fragment length, respectively.
+ * To configure incoming and outgoing I/O buffers separately, use
+ * #MBEDTLS_SSL_IN_CONTENT_LEN and #MBEDTLS_SSL_OUT_CONTENT_LEN,
+ * which overwrite the value set by this option.
+ *
+ * \note When using a value less than the default of 16KB on the client, it is
+ *       recommended to use the Maximum Fragment Length (MFL) extension to
+ *       inform the server about this limitation. On the server, there
+ *       is no supported, standardized way of informing the client about
+ *       restriction on the maximum size of incoming messages, and unless
+ *       the limitation has been communicated by other means, it is recommended
+ *       to only change the outgoing buffer size #MBEDTLS_SSL_OUT_CONTENT_LEN
+ *       while keeping the default value of 16KB for the incoming buffer.
+ *
+ * Uncomment to set the maximum plaintext size of both
+ * incoming and outgoing I/O buffers.
  */
 //#define MBEDTLS_SSL_MAX_CONTENT_LEN             16384
 
 /** \def MBEDTLS_SSL_IN_CONTENT_LEN
  *
- * Maximum incoming fragment length in bytes.
+ * Maximum length (in bytes) of incoming plaintext fragments.
  *
- * Uncomment to set the size of the inward TLS buffer independently of the
- * outward buffer.
+ * This determines the size of the incoming TLS I/O buffer in such a way
+ * that it is capable of holding the specified amount of plaintext data,
+ * regardless of the protection mechanism used.
+ *
+ * If this option is undefined, it inherits its value from
+ * #MBEDTLS_SSL_MAX_CONTENT_LEN.
+ *
+ * \note When using a value less than the default of 16KB on the client, it is
+ *       recommended to use the Maximum Fragment Length (MFL) extension to
+ *       inform the server about this limitation. On the server, there
+ *       is no supported, standardized way of informing the client about
+ *       restriction on the maximum size of incoming messages, and unless
+ *       the limitation has been communicated by other means, it is recommended
+ *       to only change the outgoing buffer size #MBEDTLS_SSL_OUT_CONTENT_LEN
+ *       while keeping the default value of 16KB for the incoming buffer.
+ *
+ * Uncomment to set the maximum plaintext size of the incoming I/O buffer
+ * independently of the outgoing I/O buffer.
  */
 //#define MBEDTLS_SSL_IN_CONTENT_LEN              16384
 
 /** \def MBEDTLS_SSL_OUT_CONTENT_LEN
  *
- * Maximum outgoing fragment length in bytes.
+ * Maximum length (in bytes) of outgoing plaintext fragments.
  *
- * Uncomment to set the size of the outward TLS buffer independently of the
- * inward buffer.
+ * This determines the size of the outgoing TLS I/O buffer in such a way
+ * that it is capable of holding the specified amount of plaintext data,
+ * regardless of the protection mechanism used.
+ *
+ * If this option undefined, it inherits its value from
+ * #MBEDTLS_SSL_MAX_CONTENT_LEN.
  *
  * It is possible to save RAM by setting a smaller outward buffer, while keeping
  * the default inward 16384 byte buffer to conform to the TLS specification.
@@ -3075,11 +3181,8 @@
  * The specific size requirement depends on the configured ciphers and any
  * certificate data which is sent during the handshake.
  *
- * For absolute minimum RAM usage, it's best to enable
- * MBEDTLS_SSL_MAX_FRAGMENT_LENGTH and reduce MBEDTLS_SSL_MAX_CONTENT_LEN. This
- * reduces both incoming and outgoing buffer sizes. However this is only
- * guaranteed if the other end of the connection also supports the TLS
- * max_fragment_len extension. Otherwise the connection may fail.
+ * Uncomment to set the maximum plaintext size of the outgoing I/O buffer
+ * independently of the incoming I/O buffer.
  */
 //#define MBEDTLS_SSL_OUT_CONTENT_LEN             16384